SMAC/Diablo inhibitors useful for treating cancer

ABSTRACT

The present invention relates to compositions and methods for treating cancer, particularly to agents that inhibit the expression and/or activity of the protein second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (SMAC/Diablo). The inhibiting agents include RNA interference molecules silencing the expression of SMAC/Diablo and peptides modulating its interactions within the cell nucleus and mitochondria. The methods and agents of the present invention are useful in treating cancers associated with overexpression of SMAC/Diablo.

The Sequence Listing in ASCII text file format of 81,175 bytes in size, created on May 10, 2021, with the file name “2021-05-10SequenceListing_SHOSHAN11,” filed in the U.S. Patent and Trademark Office on even date herewith, is hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to compositions and methods for treating cancer, particularly to agents that inhibit the expression and/or activity of the protein second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (SMAC/Diablo), including RNA interference molecules silencing the expression of SMAC/Diablo and peptides modulating its activity, useful for treating cancers associated with overexpression of SMAC/Diablo.

BACKGROUND OF THE INVENTION

The canonical SMAC/Diablo (second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI) isoform, SMAC-α, is a mitochondrial intermembrane space (IMS) pro-apoptotic protein (Verhagen, A. M., et al. 2000. Cell 102, 43-53; Du, Cet al. 2000. Cell 102, 33-42). The N-terminus of SMAC/Diablo serves as a mitochondrial targeting signal (MTS), and is cleaved to form the mature 26 kDa protein. Following the induction of apoptosis, SMAC/Diablo is released into the cytosol (Du, Cet al. 2000, ibid; Deng, Y., et al. 2002. Genes Dev. 16, 33-45), where it interacts with members of the protein family designated “inhibitor of apoptosis proteins” (IAPs), including cIAP1, cIAP2, and XIAP to neutralize the inhibitory effects of IAPB on caspases and, thus, initiates apoptosis (Shiozaki, E. N., and Shi, Y. 200). Trends Biochem. Sci. 29, 486-494; Verhagen, A. M., and Vaux, D. L. 2002. Apoptosis 7, 163-166). This interaction neutralizes the inhibitory effects of IAPB on caspases, and thus initiates apoptosis. In interacting with IAPB, SMAC/Diablo acts as a homodimer, mediated via an N-terminal motif (Ala-Val-Pro-Ile). In addition, SMAC/Diablo was shown to be controlled by several other proteins including the Bcl-2 family of proteins, mitogen-activated protein kinase family members, (e.g. Erk1/2) and c-Jun N-terminal kinase.

Although there are number of SMAC/Diablo variants generated by alternative splicing, SMAC/Diablo-α is the main IAP inhibitor (Adrain, C., et al. 2001. EMBO J 20, 6627-6636). Another isoform, SMAC/Diablo-β (Also known as SMAC-S), which lacks both the IAP-binding motif (IBM) and the MTS, can sensitize cells to apoptosis when over-expressed, suggesting that SMAC/Diablo may also serve functions that are IBM- and mitochondria-independent. A cytosolic form, SMAC/Diablo-ε, which also lacks both IBM and MTS elements, is ubiquitously expressed in normal human tissues and cancer cell lines (Martinez-Ruiz, G. U., et al., 2014. Int J Clin Exp Pathol 7, 5515-5526), is not involved in apoptosis and has been shown to be associated with tumorigenicity (Grimshaw, M. J., et al., 2008 Breast Cancer Res 10, R52). Additional isoforms of SMAC/Diablo are SMAC/Diablo-δ (also known and SMAC/Diablo-3), SMAC/Diablo-4 and SMAC/Diablo-γ (also known as SMAC/Diablo-5).

Mice lacking SMAC/Diablo are viable, grow and mature normally, present embryonic fibroblasts, lymphocytes, and hepatocytes without any histological abnormalities, and exhibit wild-type responses to all types of apoptotic stimuli (Okada, H., et al., 2002 Mol Cell Biol 22, 3509-3517).

SMAC/Diablo was found to be down-regulated in certain types of cancers. For instance, the expression levels of both SMAC/Diablo mRNA and protein were reduced in hepatocellular carcinoma cells, as compared to normal hepatic tissue (Bao, S. T., et al., 2006. Hepatobiliary Pancreat Dis Int 5, 580-583). Over-expression of recombinant SMAC/Diablo was found to sensitize neoplastic cells to apoptotic death (Kashkar, H., et al., 2006. Blood 108, 3434-3440). SMAC/Diablo or mimetic molecules thereof have been proposed as anti-cancer agents capable of inhibiting IAPB and thus promoting cancer cell death (for example, U.S. Application Publication Nos. 2013/0196927; U.S. Pat. Nos. 7,816,538, 7,884,211, and 9,861,679).

U.S. Patent Application Publication No. 2008/0253966 discloses methods for diagnosing and providing prognosis of cancer diseases that underexpress SMAC/Diablo, and methods for treating or inhibiting such diseases.

Unexpectedly, despite its role in promoting cell death, SMAC/Diablo was found to be over-expressed in some cancers and higher levels of both SMAC/Diablo protein and its encoding mRNA were reported in cervical cancer (Arellano-Llamas, A., et al., 2006. BMC Cancer 6, 256), lung, ovarian and prostate carcinomas, different types of sarcoma (Yoo, N. J., et al., 2003. APMIS 111, 382-388), gastric carcinomas (Shintani, M., et al., 2014. Oncol Lett 8, 2581-2586), pancreatic cancer (Hu H. Y. et al., 2012. Hepatogastroenterology 59(120):2640-3), testis cancer (Yoo N. J. et al., 2003. APMIS 111(3):382-388) and renal cell carcinoma (Kempkensteffen, C., et al., 2008. J Cancer Res Clin Oncol 134, 543-550).

There is a growing awareness of the understanding that cancer is not a single disease. Thus, there is a need for and it would be highly advantageous to have compositions and methods for treating cancer diseases that share common characteristics.

SUMMARY OF THE INVENTION

The present invention provides compositions and methods for treating cancers that overexpress SMAC/Diablo. The present invention provides agents that inhibit the expression and/or activity of SMAC/Diablo. In particular embodiments the present invention provides RNA inhibitory agents that silence or otherwise down regulate the expression of SMAC/Diablo and peptides that interact with SMAC/Diablo protein within the mitochondria and/or nucleus.

The present invention is based in part on the unexpected discovery that silencing the expression of SMAC/Diablo encoding mRNA, using small interfering RNA (siRNA) molecules, in cancer cell lines overexpressing the mRNA and encoded protein, markedly reduced the cell proliferation. Silencing SMAC/Diablo in mice subcutaneous xenografts of lung cancer cells or of breast triple negative cancer cells significantly reduced tumor growth. Furthermore, following SMAC/Diablo silencing treatment, residual lung tumors demonstrated morphological changes, including the development of alveoli-like anatomical structures and elimination of intracellular organelles, such as lamellar bodies, which are typical to alveolar type 2 (AT2) cells in lung tissue and non-small cells lung carcinoma cells. Next-generation sequencing of mRNA material obtained from tumors treated with SMAC-silencing siRNA molecules revealed altered expression of genes associated with intercellular membranal and exosomal networks, cells differentiation, lipid metabolism and transport activities. SMAC/Diablo silencing in lung cancer tumors decreased the level of phospholipids, including phosphatidylcholine, and the expression of enzymes associated with their synthesis. The present invention further discloses peptides derived from proteins interacting with SMAC/Diablo and modulate its activity. The peptides specifically bind to SMAC/Diablo and, when targeted into the mitochondria and/or nucleus of cancerous cells overexpressing SMAC/Diablo, inhibit the cell proliferation.

According to one aspect, the present invention provides a method for treating cancer associated with over-expression of second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (SMAC/Diablo) in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of at least one agent that inhibits the expression and/or activity of the SMAC/Diablo.

According to certain exemplary embodiments, inhibiting the expression and/or activity of SMAC/Diablo results in reduced proliferation of cancerous cells.

According to certain embodiments, the agent that inhibits the expression and/or activity of SMAC/Diablo is selected from the group consisting of an inhibitory nucleic acid, an inhibitory peptide, an inhibitory small molecule, an inhibitory aptamer, and combinations thereof.

According to certain embodiments, the agent is SMAC/Diablo silencing oligonucleotide or a recombinant construct encoding same, targeted to the gene or mRNA sequence encoding SMAC/Diablo protein.

According to certain embodiments, the SMAC/Diablo encoding gene comprises a nucleic acid sequence at least 80%, at least 85%, at least 90%, at least 95% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:1 (NG_029459.1).

According to certain embodiments, the SMAC/Diablo protein is selected from the group consisting of SMAC/Diablo-α, having an amino acids sequence at least 80%, at least 85%, at least 90% or more homologous to the amino acid sequence set forth in SEQ ID NO:2; SMAC/Diablo-δ, having an amino acids sequence at least 80%, at least 85%, at least 90% or more homologous to the amino acid sequence set forth in SEQ ID NO:4; SMAC/Diablo-β, having an amino acids sequence at least 80%, at least 85%, at least 90% or more homologous to the amino acid sequence set forth in SEQ ID NO:6; SMAC/Diablo-4, having an amino acids sequence at least 80%, at least 85%, at least 90% or more homologous to the amino acid sequence set forth in SEQ ID NO:8; and SMAC/Diablo-γ, having an amino acids sequence at least 80%, at least 85%, at least 90% or more homologous to the amino acid sequence set forth in SEQ ID NO:10. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the SMAC/Diablo-α is encoded by a nucleic acid sequence at least 80%, at least 85%, at least 90% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:3 (NM_019887.5); the SMAC/Diablo-δ is encoded by a nucleic acid sequence at least 80%, at least 85%, at least 90% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:5 (NM_001278342.1); the SMAC/Diablo-β is encoded by a nucleic acid sequence at least 80%, at least 85%, at least 90% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:7 (NM_001278304.1; NM_138930.3); the SMAC/Diablo-4 is encoded by a nucleic acid sequence at least 80%, at least 85%, at least 90% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:9 (NM_001278302.1); and the SMAC/Diablo-γ is encoded by a nucleic acid sequence at least 80%, at least 85%, at least 90% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:11 (NM_001278303.1). Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the SMAC/Diablo protein is human protein (hSMAC/Diablo)selected from the group consisting of hSMAC/Diablo-α, having the amino acid sequence set forth in SEQ ID NO:2; hSMAC/Diablo-δ, having the amino acid sequence set forth in SEQ ID NO:4; hSMAC/Diablo-δ, having the amino acid sequence set forth in SEQ ID NO:6; hSMAC/Diablo-4, having the amino acid sequence set forth in SEQ ID NO:8; and hSMAC/Diablo-γ, having the amino acid sequence set forth in SEQ ID NO:10. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the hSMAC/Diablo-α is encoded by the nucleic acid sequence having SEQ ID NO:3; hSMAC/Diablo-δ is encoded by the nucleic acid sequence having SEQ ID NO:5; hSMAC/Diablo-β is encoded by the nucleic acid sequence having SEQ ID NO:7; hSMAC/Diablo-4 is encoded by the nucleic acid sequence having SEQ ID NO:9; and hSMAC/Diablo-γ is encoded by the nucleic acid sequence having SEQ ID NO:11. Each possibility represents a separate embodiment of the present invention.

According to some embodiments, the SMAC/Diablo protein is selected from the group consisting of SMAC/Diablo-α and SMAC/Diablo-δ.

According to certain embodiments, the SMAC/Diablo silencing molecule comprises at least 15 consecutive nucleic acid bases targeted to (hybridizable with) a nucleic acid sequence encoding SMAC/Diablo protein or to a complementary polynucleotide thereof.

According to certain embodiments, the SMAC/Diablo silencing molecule comprises at least 15 consecutive nucleic acid bases substantially identical to a nucleic acid sequence at least 80%, at least 85%, at least 90% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:3 or to a nucleic acid sequence complementary to SEQ ID NO:3.

According to certain exemplary embodiments, the SMAC/Diablo protein is hSMAC/Diablo-α having the amino acid sequence set forth in SEQ ID NO:2, encoded by the nucleic acid sequence set forth in SEQ ID NO:3.

According to certain embodiments, the SMAC/Diablo silencing molecule comprises at least 15 consecutive nucleic acid bases substantially homologous to nucleic acid bases at positions 900-1,500 of SEQ ID NO:3 or to a complementary polynucleotide thereof.

According to certain embodiments, the inhibitory nucleic acid comprises a nucleic acid sequence selected from the group consisting of SEQ ID NOs:12-17, 20-25, and 28-43, a DNA or RNA sequence corresponding thereto, analogs, derivatives and combinations thereof. Each possibility represents separate embodiment of the present invention.

According to certain embodiments, the inhibitory nucleic acid is selected from the group consisting of an interfering RNA (RNAi), an antisense polynucleotide, a catalytic RNA, and an RNA-DNA chimera.

According to certain embodiments, the nucleic acid agent inhibiting the expression of SMAC/Diablo (SMAC/Diablo silencing oligonucleotide) is selected from the group consisting of RNA interference (RNAi) molecule and antisense molecule. According to some embodiments, the RNAi molecule is an unmodified and/or modified double stranded (ds) RNA molecules including, but not limited to, short-temporal RNA (stRNA), small interfering RNA (siRNA), short-hairpin RNA (shRNA), and microRNA (miRNA). In some embodiments, the SMAC/Diablo inhibitor is a biosynthetic precursor of a SMAC/Diablo-targeted dsRNA.

According to certain exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is siRNA. siRNAs are typically short double-stranded RNA species with phosphorylated 5′ ends and hydroxylated 3′ ends. The siRNA molecules of the invention comprise a first oligonucleotide and a second oligonucleotide essentially complementary thereto (sense and antisense RNA strands) that can form an RNA duplex. Typically, each strand of the siRNA molecule is no more than 30 nucleotides in length, and is preferably about 19-25 nucleotides in length.

The siRNA molecules may further comprise 3′ nucleotide overhangs on either or both strands, i.e. terminal portions of the nucleotide sequence that are not base paired between the two strands of the double stranded siRNA molecule. Preferably, the overhang is about 1-5 nucleotides in length, more preferably 2 nucleotides in length.

According to certain embodiments, the SMAC/Diablo silencing oligonucleotide is siRNA molecule comprising a first oligonucleotide comprising a nucleic acid sequence substantially homologous to at least 15 consecutive nucleic acid bases of SEQ ID NO:3 and a second polynucleotide sequence substantially complementary to the first oligonucleotide; wherein said first and second oligonucleotides are able to anneal to each other to form the siRNA molecule.

According to certain exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is an siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:12 (AAGCGGUGUUUCUCAGAAUUG) and a second oligonucleotide substantially complementary thereto. According to some embodiments, the second oligonucleotide comprises the nucleic acid sequence set forth in SEQ ID NO:13 (AACAAUUCUGAGAAACCCGC). According to certain further exemplary embodiments, the targeted SMAC/Diablo polynucleotide comprises the nucleic acid sequence set forth in any one of SEQ ID NO:3 and SEQ ID NO:5.

According to certain exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is an siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:14 (GCAGAUCAGGCCUCUAUAA) and a second oligonucleotide substantially complementary thereto. According to some embodiments, the second oligonucleotide comprises the nucleic acid sequence set forth in SEQ ID NO:15 (UUAUAGAGGCCUGAUCUGC). According to certain further exemplary embodiments, the targeted SMAC/Diablo polynucleotide comprises the nucleic acid sequence set forth in any one of SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, and SEQ ID NO:11.

According to certain exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is an siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:16 (CCCGGAAAGCAGAAACCAA) and a second oligonucleotide substantially complementary thereto. According to some embodiments, the second oligonucleotide comprises the nucleic acid sequence set forth in SEQ ID NO:17 (UUGGUUUCUGCUUUCCGGG). According to certain further exemplary embodiments, the targeted SMAC/Diablo polynucleotide comprises the nucleic acid sequence set forth in any one of SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, and SEQ ID NO:11.

According to certain embodiments, the first and/or the second oligonucleotide of the siRNA molecules of the present invention further comprises 3′ overhang of two thymine nucleotides. According to these embodiments, the SMAC/Diablo siRNA molecule is selected from the group consisting of an siRNA molecule comprising a first nucleotide having the nucleic acid sequence set forth in SEQ ID NO:20 and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:21; an siRNA molecule comprising a first nucleotide having the nucleic acid sequence set forth in SEQ ID NO:22 and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:23; and an siRNA molecule comprising a first nucleotide having the nucleic acid sequence set forth in SEQ ID NO:24 and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:25. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the SMAC/Diablo silencing oligonucleotide is chemically modified. According to some embodiments, the SMAC/Diablo silencing oligonucleotide comprises at least one 2′-sugar modification. In a particular embodiment, the 2′-sugar modification is a 2′-O-methyl (2′-O-Me) modification.

According to certain embodiments, the SMAC/Diablo silencing oligonucleotide is modified (typically by a 2′-O-Me) at least at one position selected from the group consisting of position 3, 5, 6, 7, 9, 10, 11, 16 and 21 of SEQ ID NO:12 or SEQ ID NO:20.

According to certain embodiments, the hSMAC/Diablo silencing oligonucleotide is modified (typically by a 2′-O-Me) at least at one position selected from the group consisting of position 6, 7, 10, 12, and 19 of SEQ ID NO:13 or SEQ ID NO:21.

According to some exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is an siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:20 derivatized by 2-O′-Me at positions 5, 10, 16 and 21 (SEQ ID NO:28) and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:21 derivatized by 2-O′-Me at positions at positions 6, 12 and 19 (SEQ ID NO:29).

According to some exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is an siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:20 derivatized by 2-O′-Me at positions 3, 6, 11, and 21 (SEQ ID NO:34) and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:21 derivatized by 2-O′-Me at positions at positions 6, and 19 (SEQ ID NO:35).

According to certain embodiments, the SMAC/Diablo silencing oligonucleotide is modified (typically by a 2′-O-Me) at least at one position selected from the group consisting of position 4, 6, 9, 10, 13, 15 and 17 of SEQ ID NO:14 or SEQ ID NO:22.

According to certain embodiments, the hSMAC/Diablo silencing oligonucleotide is modified (typically by a 2′-O-Me) at least at one position selected from the group consisting of position 2, 4, 6, 8, 9, 12, 13, 15, 17 and 18 of SEQ ID NO:15 or SEQ ID NO:23.

According to some exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is an siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:22 derivatized by 2-O′-Me at positions 4, 9, 13, and 17 (SEQ ID NO:38) and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:7 derivatized by 2-O′-Me at positions at positions 6, 12, and 18 (SEQ ID NO:39).

According to some exemplary embodiments, the SMAC/Diablo silencing oligonucleotide is an siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:22 derivatized by 2-O′-Me at positions 6, 10, and 15 (SEQ ID NO:40) and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:23 derivatized by 2-O′-Me at positions at positions 2, 9, and 17 (SEQ ID NO:41).

According to some embodiments, the siRNA is a single-stranded short hairpin RNA (shRNA) wherein the first oligonucleotide sequence is separated from the second oligonucleotide sequence by a linker which forms a loop structure upon annealing of the first and second oligonucleotide sequences. In some embodiments the linker length is about 3 to about 60 nucleotides.

According to certain embodiments, the method of the present invention comprises administering to the subject a nucleic acid construct capable of expressing at least one inhibitory nucleic acid.

According to some embodiments, the expressed inhibitory nucleic acid comprises a sequence selected from the group consisting of SEQ ID NOs:12-17, 20-25, 28-29, 34-35 and 38-41. According to certain embodiments, the nucleic acid construct is capable of expressing at least one siRNA molecule. According to certain exemplary embodiments, the method comprises administrating to the subject a construct capable of expressing siRNA molecule comprising a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:12 or SEQ ID NO:20 and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:13 or SEQ ID NO:21.

The present invention discloses novel peptides derived from hSMAC/Diablo-associated proteins that can bind to hSMAC/Diablo. When the peptide derived from hSMAC/Diablo-interacting protein is targeted into the cell and further into the nucleus and/or the mitochondria, such that the interaction with hSMAC/Diablo occurs within the organelle(s), the interaction results in inhibition or intervention in phospholipid biosynthesis, cell growth and/or cell proliferation.

According to further embodiments of the invention, the agent that inhibits the activity of SMAC/Diablo is an inhibitory peptide targeted to the nucleus and/or to the mitochondria of a cell. According to certain embodiments, the cell is overexpressing SMAC/Diablo.

According to certain embodiments, the inhibiting peptide is a conjugate comprising a peptide derived from hSMAC/Diablo-interacting protein having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and a mitochondria and/or nucleus targeting moiety. The mitochondria and/or nucleus targeting moiety can be peptidic or non-peptidic, and is covalently linked to the peptide derived from SMAC/Diablo-interacting protein directly or via linker. The targeting moiety may be linked to the peptide derived from hSMAC/Diablo-interacting protein at any position. According to some embodiments, the targeting moiety is linked to the N- or the C-terminus of the peptide derived from hSMAC/Diablo-interacting protein. When the conjugate comprises a combination of mitochondria and nucleus targeting moieties each moiety may be independently linked to the N- or C-terminus of the peptide or the mitochondria and nucleus targeting moieties can be linked in tandem to the N- or C-terminus of the peptide. According to some embodiments, the conjugate further comprises a cell penetration moiety enhancing the permeability of the conjugate through the cell plasma membrane. Any cell penetrating moiety as is known in the art can be used according to the teachings of the present invention.

According to some embodiments, the inhibiting peptide is a conjugate of a peptide derived from hSMAC/Diablo-interacting protein having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and a nucleus targeting moiety. Any nucleus targeting (localization) moiety as is known in the art can be used according to the teachings of the present invention. According to certain exemplary embodiments, the nucleus targeting moiety is the tetrapeptide RrRK, wherein r is D-arginine (SEQ ID NO:68). The nucleus targeting tetrapeptide can be independently located at the C- or N-terminus of the peptide derived from hSMAC/Diablo-interacting protein.

According to some embodiments, the inhibiting peptide is a conjugate of a peptide derived from hSMAC/Diablo-interacting protein having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and a mitochondria targeting moiety. Any mitochondria targeting (localization) moiety as is known in the art can be used according to the teachings of the present invention. According to certain exemplary embodiments, the mitochondria targeting moiety comprises the amino acid sequence set forth in SEQ ID NO:72. The mitochondria targeting peptide can be independently located at the C- or N-terminus of the peptide derived from hSMAC/Diablo-interacting protein. When the mitochondria targeting peptide having SEQ ID NO:72 is located at the C-terminus of the peptide derived from hSMAC/Diablo-interacting protein, its C-terminus may be amidated.

According to certain embodiments, the peptide derived from hSMAC/Diablo-interacting protein comprises an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67. According to some embodiments, the peptide derived from hSMAC/Diablo-interacting protein comprises an amino acid sequence selected from the group consisting of SEQ ID NO:46, SEQ ID NO:47, SEQ ID NO:48 and SEQ ID NO:49. Each possibility represents a separate embodiment of the present invention.

According to certain exemplary embodiments, the inhibiting peptide conjugate targeted to the nucleus comprises an amino acid sequence selected from the group consisting of SEQ ID NO:69, SEQ ID NO: 70 and SEQ ID NO:71.

According to certain exemplary embodiments, the inhibiting peptide conjugate targeted to the mitochondria comprises an amino acid sequence selected from the group consisting of SEQ ID NO:73 and SEQ ID NO:74.

According to certain embodiments, the cancer is selected from the group consisting of lung cancer, breast cancer, colon cancer, lymphoma, sarcomas, stomach cancer, skin cancer, renal cancer, prostate cancer, testicular cancer, cervical cancer, leukemia and pancreatic cancer. Each possibility represents a separate embodiment of the present invention.

According to certain currently exemplary embodiments, the cancer is lung cancer.

According to certain additional currently exemplary embodiments, the cancer is breast cancer.

According to certain embodiments treating the cancer comprises re-programming the cancerous cells to at least one of attenuated lipid synthesis, decreased proliferation, and differentiation.

According to certain exemplary embodiments, the cancer is lung cancer and treating the lung cancer comprises at least one of inducing differentiation of AT2-like cells to differentiated non-proliferating AT1 cells; reducing proliferation of AT2-like undifferentiated cells and a combination thereof. These activities lead to the appearance of alveolar healthy-like morphology.

Any method as is known in the art for administering the agent that inhibits the expression and/or activity of the SMAC/Diablo can be used according to the teachings of the present invention. According to some embodiment, the inhibitory agent is administered within a pharmaceutical composition. According to certain exemplary embodiments, the pharmaceutical composition further comprises pharmaceutically acceptable excipients, diluents or carriers.

According to certain embodiments, the inhibitory agent is an RNA inhibitory molecule or a peptide. According to certain currently exemplary embodiments, the inhibitory agent is siRNA molecule. According to additional certain currently exemplary embodiments, the inhibitory agent is a peptide conjugate comprising a peptide derived from hSMAC/Diablo-interacting protein and a nucleus and/or mitochondria targeting moiety. According to these embodiments, the RNAi molecule, the construct comprising same or the peptide conjugate is administered within a pharmaceutical composition, said pharmaceutical composition optionally further comprises pharmaceutically acceptable excipients, diluents or carriers.

According to additional exemplary embodiments, the RNAi molecule is encapsulated within a nanoparticle or a liposome. According to some embodiments, the RNAi molecule is encapsulated within Polyethylenimine (PEI)-Poly(D,L-lactide-co-glycolide) (PLGA) nanoparticle or any other siRNA-delivery system as is known in the art.

The mode of administering the inhibitory agent according to the teachings of the present invention will depend upon the type of the agent, the type and severity of the cancer and parameters related to the subject (age, gender, weight etc.).

According to certain embodiments, the inhibitory agent or a pharmaceutical composition comprising same is administered via intravenous, intradermal, intramuscular, intra-arterial, intralesional, percutaneous, subcutaneous, intranasal or oral administration or by inhalation or by aerosol administration, or by combinations thereof. In some embodiments, administration is prophylactic administration, and in alternative embodiments, administration is therapeutic administration. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the method of the present invention further comprises administering to the subject at least one additional anti-cancer agent or anti-cancer therapy.

Any agent and/or therapy as is known in the art for treating the cancerous disease of the subject can be employed as long as its activity does not interfere with the inhibition of SMAC/Diablo expression and/or activity according to the teachings of the present invention.

According to another aspect, the present invention provides at least one agent that inhibits the expression and/or activity of SMAC/Diablo for use in treating cancer associated with over-expression of SMAC/Diablo.

According to additional aspect, the present invention provides the use of at least one agent that inhibits the expression and/or activity of SMAC/Diablo for the preparation of a medicament for treating cancer associated with over-expression of SMAC/Diablo.

The at least one agent and the cancer types are as described hereinabove.

According to further aspect, the present invention provides an isolated SMAC/Diablo silencing molecule comprising a first oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:12 and optionally a 3′ overhang of 1-5 nucleotides, derivatized by 2′-O-methyl (2′-O-Me) at positions 5, 10, 16, and 21 and a second oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:13 and optionally a 3′ overhang of 1-5 nucleotides, derivatized by 2′-O-Me at positions 6, 12 and 19.

According to certain embodiments, the SMAC/Diablo silencing oligonucleotide comprising a first oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:20 derivatized by 2′-O-Me at positions 5, 10, 16, and 21 and a second oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:21 derivatized by 2′-O-Me at positions 6, 12 and 19.

According to yet further aspect, the present invention provides an isolated SMAC/Diablo silencing molecule comprising a first oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:12 and optionally a 3′ overhang of 1-5 nucleotides, derivatized by 2′-O-methyl (2′-O-Me) at positions 3, 6, 11 and 21, and a second oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:13 and optionally a 3′ overhang of 1-5 nucleotides, derivatized by 2′-O-Me at positions 6 and 19.

According to certain embodiments, the SMAC/Diablo silencing molecule comprises a first oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:20 derivatized by 2′-O-Me at positions 3, 6, 11, and 21 and a second oligonucleotide comprising the nucleic acid sequence set forth in SEQ ID NO:21 derivatized by 2′-O-Me at positions 6 and 19.

According to additional aspect, the present invention provides an isolated SMAC/Diablo silencing molecule comprises a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:14 and optionally a 3′ overhang of 1-5 nucleotides and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:15 and optionally a 3′ overhang of 1-5 nucleotides. According to certain embodiments, the first oligonucleotide is derivatized by 2′-O-Me at positions 4, 9, 13 and 17 and the second oligonucleotide is derivatized by 2′-O-Me at positions 6, 12 and 18. According to other embodiments, the first oligonucleotide is derivatized by 2′-O-Me at positions 6, 10, and 15 and the second oligonucleotide is derivatized by 2′-O-Me at positions 2, 9 and 17.

According to some embodiments, the isolated SMAC/Diablo silencing molecule comprises a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:22 and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:23. According to certain embodiments, the first oligonucleotide is derivatized by 2′-O-Me at positions 4, 9, 13 and 17 and the second oligonucleotide is derivatized by 2′-O-Me at positions 6, 12 and 18. According to other embodiments, the first oligonucleotide is derivatized by 2′-O-Me at positions 6, 10, and 15 and the second oligonucleotide is derivatized by 2′-O-Me at positions 2, 9 and 17.

According to additional aspect, the present invention provides an isolated SMAC/Diablo silencing molecule comprises a first oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:16 and optionally a 3′ overhang of 1-5 nucleotides and a second oligonucleotide having the nucleic acid sequence set forth in SEQ ID NO:17 and optionally a 3′ overhang of 1-5 nucleotides. According to certain embodiments, the first oligonucleotide comprises the nucleic acid sequence set forth in SEQ ID NO:24 and the second oligonucleotide comprises the nucleic acid sequence set forth in SEQ ID NO:25.

According to yet additional aspect, the present invention provides an isolated synthetic or recombinant peptide having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, an analog, derivative or a fragment thereof, wherein the peptide is capable of binding to human SMAC/Diablo. According to certain embodiments, the peptide comprises the amino acid sequence set forth in any one of SEQ ID NOs:46-67.

According to certain embodiments, the peptide further comprises a nucleus and/or mitochondria targeting moiety. The nucleus or mitochondria targeting moiety can be linked to the peptide at any position, typically at the N- or at the C-terminus, directly or via a linker. According to some embodiments, the conjugate further comprises a cell-penetrating moiety.

According to certain embodiments, the present invention provides a peptide conjugate comprising a peptide having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, an analog, derivative or a fragment thereof, and a nucleus targeting peptide having the amino acid sequence set forth in SEQ ID NO:68. According to some embodiments, the peptide conjugate comprises a peptide having an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, an analog, derivative or a fragment thereof, and a nucleus targeting peptide having the amino acid sequence set forth IN SEQ ID NO:68. According to certain exemplary embodiments, the peptide conjugate comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 69, SEQ ID NO:70, and SEQ ID NO:71. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the present invention provides a peptide conjugate comprising a peptide having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, an analog, derivative or a fragment thereof, and a mitochondria targeting peptide having the amino acid sequence set forth IN SEQ ID NO:72. According to some embodiments, the peptide conjugate comprises a peptide having an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, an analog, derivative or a fragment thereof, and a nucleus targeting peptide having the amino acid sequence set forth IN SEQ ID NO:72. According to certain exemplary embodiments, the peptide conjugate comprises an amino acid sequence selected from the group consisting of SEQ ID NO:73, and SEQ ID NO:74. Each possibility represents a separate embodiment of the present invention.

It is to be understood explicitly that the scope of the present invention encompasses homologs, analogs, variants and derivatives, including shorter and longer peptides, polypeptides, proteins and polynucleotides, as well as peptides, polypeptides, proteins and polynucleotide analogs with one or more amino acid or nucleic acid substitution, as well as amino acid or nucleic acid derivatives, non-natural amino or nucleic acids and synthetic amino or nucleic acids as are known in the art, with the stipulation that these variants and modifications must preserve the capacity of inhibiting the expression and/or the activity of SMAC/Diablo according to the teachings of the present invention.

It is to be understood that any combination of each of the aspects and the embodiments disclosed herein is explicitly encompassed within the disclosure of the present invention.

Other objects, features and advantages of the present invention will become clear from the following description and drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 demonstrates SMAC/Diablo over-expression in various types of tumors and cell lines: (A) Representative IHC staining of SMAC/Diablo in normal (n=5) and cancerous (n=20) tissue samples from tissue microarray slides (Biomax). The percentages of samples that stained at the indicated intensities are denoted; (B) Representative immunoblot staining of tissue lysates of healthy (H) and tumor (T) tissues with anti-SMAC/Diablo antibodies, with each pair of samples (H,T) being derived from the same patient lung; (C) Representative immunoblots showing SMAC/Diablo expression in PBMCs derived from CLL patients or healthy donors. As a loading control, actin levels were probed using anti-β-actin antibodies; (D) Quantitative analysis of SMAC/Diablo expression levels indicating the fold increase in the NSCLC tumor, in comparison to healthy tissue from the same patient (n=20), and in PBMCs from CLL patients, as compared to healthy donors (n=32); and (E, F) SMAC/Diablo expression levels in different cell lines, with the levels in the cancer cells being presented relative to those in the non-cancerous cells (bottom of the blot).

FIG. 2 demonstrates inhibition of cell growth resulted from silencing of SMAC/Diablo using si-hSMAC-A: (A) The indicated cancer cell lines were transfected with si-hSMAC-A (50 nM) and 48 h post-transfection, levels of SMAC/Diablo in the cells were evaluated by immunoblotting FIG. 2A). β-actin was used as a loading control; (B, D) A549 and H358 cells (B) and HeLa cells (D) were transfected with si-NT or si-hSMAC-A and at the indicated time, cells were harvested and analyzed for SMAC/Diablo levels by immunoblotting. β-actin was used as a loading control. (C, E) Quantitative analysis of the immunoblots of A549 and H358 cells (C) and HeLa cells (E) represented SMAC/Diablo level relative to the respective untreated cells, at 24 h (black bar), 48 h (dark gray bar), 72 h (light gray bar) and 96 h (white bar) (n=3); (F) HeLa, A549 and H358 cells were untreated (●), transfected with non-targeted siRNA (si-NT) (∘) or SMAC/Diablo-A targeted siRNA (si-hSMAC-A) (50 nM) (▴). Cell growth was assayed at the indicated times using the SRB method (n=3); (G, H) The A549, H358, WI-38 and HaCaT cell lines were transfected with the indicated concentration (10-50 nM) of si-NT or si-hSMAC-A. After 48 h, (G) SMAC/Diablo levels in the cells were analyzed by immunoblotting and (H) cell growth was assayed; (I) A549 cells were transfected with si-NT or si-hSMAC B, C, or D (50 nM) and at the indicated times, cells were harvested and analyzed for SMAC/Diablo levels by immunoblotting. β-actin was used as a loading control. (J) Bar graph represents inhibition of growth of A549 cells treated with si-NT or si-hSMAC B, C, or D (50 nM). (K) Quantitative analysis of Ki-67 positive cells of si-NT- or si-hSMAC-A (50 nM)-treated A549 cells, as analyzed from immunofluorescence staining for Ki-67 (L) Cell cycle analysis of A549 cells treated with si-hSMAC (50 nM) by flow cytometry. Cells incubated with etoposide (10 μM, 24 h) were used as positive control. (M) ATP levels were analyzed at 24, 48 and 72 h post-transfection in HeLa (black bar), A549 (dark gray bar) and H358 cells (light gray bar) treated with si-NT or si-hSMAC-A (50 nM).

FIG. 3 depicts cell death induced by overexpression of exogenous SMAC/Diablo: (A) Bar-graph represents % of cell death induced by si-NT or si-hSMAC-A (50 nM) or selenite (5 μM) in HeLa, A549 and H358 cells. Cells were transfected with si-NT or si-hSMAC-A and analyzed for cell death after 24 h (white bar), 48 h (black bar) and 72 h (gray bar) using propidium iodide (PI) staining by flow cytometry. Selenite (5 μM) used as positive control; (B) Representative cell death analysis of A549 cells treated with si-NT or si-hSMAC-A (50 nM, 48 h) or selenite (10 μM, 24 h) using FITC-Annexin V/PI staining and flow cytometry. (C) Qantitative analysis of cell deathin cells treated for the indicated time with 50 nM si-NT (black bar) or si-hSMAC-A (gray bar) or selenite using FITC-Annexin V/PI staining by flow cytometry. (D, E) Representative immunoblot staining by anti-SMAC/Diablo antibodies of cell lysate from HeLa, A549 and H358 cells 48 h of post-transfection with pEGFP encoding plasmid (D) or SMAC/Diablo-GFPpcDNA 3.1 plasmid (0.75 μg) (E); (F) Bar-graph representing % of cell death induced by GFP or SMAC/Diablo-GFPpcDNA 3.1 plasmid (1 μg-2 μg) in HeLa, A549 and H358 cells. Cells death was analyzed after 24 and 48 hour using PI staining by flow cytometry.

FIG. 4 depicts inhibition by si-hSMAC-A of tumor growth of lung cancer xenografts: (A) A549 cells were inoculated into nude mice (3×10⁶ cells/mouse). Tumor volumes were monitored, and on day 18, mice with similar average tumor volumes (75-90 mm³) were divided into three groups (n=5). Xenografts were injected with si-NT (●, 50 nM) or si-hSMAC (350 nM (∘) or 700 nM (▴)). The size of the xenografts was measured and average tumor volumes are presented as means±SEM, p:**≤0.01; p: ***≤0.001; (B) Representative tumors; (C) Weights of dissected tumors from mouse A549 cell xenografts after treatment with si-NT (si-NT treated tumors, si-NT-TTs) or si-hSMAC-A (si-hSMAC treated tumors, si-hSMAC-A-TTs); (D) Representative sections from si-NT-TTs and si-hSMAC-A-TTs stained with anti-SMAC/Diablo antibodies; (E) Expression of α- and ε-SMAC/Diablo isoforms in RNA isolated from si-NT- and si-hSMAC-A-TTs using PCR and specific primers; (F) Representative sections from si-NT-TTs and si-hSMAC-A-TTs stained with anti-Ki-67 antibodies; and (G) Quantitative analysis of Ki-67 protein (grey bars) and mRNA (q-PCR) (black bars) levels in si-NT- and si-hSMAC-A-TTs.

FIG. 5 depicts that si-hSMAC-A inhibited cell growth in vitro and tumor growth of breast cancer xenografts: (A) MDA-MB-231 cells were transfected with si-NT (50 nM) or si-hSMAC-A (100 nM) and analyzed for cell growth at the indicated time using the SRB method (n=3) (Control (●), si-NT (∘), si-hSMAC-A (▴); (B) MDA-MB-231 cells were transfected with si-NT or si-hSMAC-A and at the indicated time cells were harvested and analyzed for SMAC/Diablo levels by immunoblotting. β-actin was used as a loading control; (C) MDA-MB-231 cells (3×10⁶cells/mouse) were inoculated into nude mice. Tumor volumes were monitored (using a digital caliper) and on day 18, the mice were divided into two groups (n=8 each) with each mouse in the group containing a tumor with a volume between 60 and 100 mm³ and similar average volumes measured per group. The two mice groups were subjected to the following treatments: Xenografts were injected with si-NT (●, 350 nM) or si-hSMAC-A (▴, 700 nM). (D) Represents photomicrograph of dissected tumors from mouse MDA-MB-231 cell xenografts treated with si-NT or si-hSMAC-A; (E) Bar-graph represents dissected tumors weight from MDA-MB-231 cell xenografts; calculated average tumor volumes are presented as means±SEM, ***P<0.001 (F, G) Dissected tumors were subjected to immunohistochemistry. Photomicrographs represent IHC staining of tumor sections from three mice from each group with (F) anti-SMAC/Diablo and (G) anti-Ki-67 antibodies. Bars represent 50 μm.

FIG. 6 depicts that silencing of SMAC/Diablo affects the expression of its associated proteins: (A, B) mRNA levels of SMAC/Diablo, XIAP, cIAP1, cIAP2, cytochrome c, AIF caspase 8, 9 and 3 as analyzed using q-PCR in siNT-TTs relative to si-hSMAC-A-TT (presented as fold change). (C) HeLa, A549 and H358 cells were transfected with si-NT or si-hSMAC-A (50 nM) and at the indicated time cells were harvested and analyzed for SMAC/Diablo, XIAP, Caspase 8, 9 and 3 by immunoblotting. β-actin was used as a loading control; (D) Quantitative analysis of the immunoblot was carried out and presented (relative units (RU)) for all cell lines at the 48 h (gray bar) and 96 h (black bar) of post-transfection (n=3); (E) Bar graph represents relative mRNA levels of SMAC/Diablo, XIAP, cIAP1 and cIAP2 using q-PCR technique in HeLa, A549 and H358 cells after 48 h (gray bar) and 96 h (black bar) of post-transfection with si-hSMAC-A (50 nM).

FIG. 7 depicts the morphological changes induced in tumors treated with si-hSMAC: (A) Representative sections from si-NT- and si-hSMAC-A-TTs stained with H&E; (B) Enlarged images of representative sections from si-NT- and si-hSMAC-A-TTs stained with H&E, showing glandular-like clusters surrounded by a chain of cells (arrows) in si-hSMAC-A-TTs; (C, D, E) Sections from si-NT- and si-hSMAC-A-TTs stained with anti-prosurfactant c (C) or anti-podoplanin antibodies (D, E); (F) Representative sections from si-NT- and si-hSMAC-A-TTs stained with anti-CD31 antibodies; and (G, H) Schematic presentations of alveoli (H) and a cross-section through alveoli, with major cell types indicated (I).

FIG. 8 depicts the staining of stromal markers in si-NT-TTs and si-hSMAC-A-TTs: (A) Representative sections from si-NT-TTs and si-hSMAC-A-TTs stained with H&E showing stromal structures; (B) vascular formation with red blood cells (arrows) in si-NT-TTs but not si-hSMAC-A-TTs; and (C) with anti-α-SMA antibodies.

FIG. 9 depicts the nuclear and mitochondrial localization of SMAC/Diablo: (A) Representative sections from si-NT-TTs derived from A549 cells stained with anti-SMAC/Diablo antibodies and viewed by immunofluorescence. (B, C) IHC staining of SMAC/Diablo expression in cancerous lung tissue from tissue microarray slides (Biomax) indicating nuclear (B) and cytosolic (C) localization of SMAC/Diablo.

FIG. 10 depicts the differentially expressed genes and subcellular morphological alterations induced by reductions in SMAC levels in lung cancer cell derived xenografts: NGS data analysis showing selected down-regulated (A) and up-regulated (B) genes associated with the extracellular matrix, including cell-secreted collagen and proteoglycans, extracellular exosomes and proteins in the endoplasmic reticulum and Golgi lumen associated with vesicle formation. The number of genes and p-values are indicated for each category; (C) Changes (as revealed by NGS) in the expression of genes associated with lipid transport, synthesis, and degradation in si-hSMAC-A-TTs, represented as fold change, relative to their expression in si-NT-TTs; (D) Representative electron microscopic images of si-NT-TTs and si-hSMAC-A-TTs sections. Arrows points to lamellar bodies; (E) The levels of phosphatidylcholine (PC), phosphatidylethanol amine (PE) and total phospholipids (PL) in si-hSMAC-A-TTs, relative to si-NT-TTs, determined as described hereinabove; and (F) Changes in the expression of mRNA (q-PCR) associated with phosphatidylcholine synthesis in si-hSMAC-A-TTs, presented as fold change. (G) Schematic representation of diacylglycerols (a) and phosphatidylcholine synthesis (b, c) pathways, with down- and up-regulated genes identified by arrows.

FIG. 11 depicts the genes associated with transporters, metabolism, inflammatory response, exosome and vesicles formation, differentially expressed between si-NT-TTs and si-hSMAC-A-TTs: results from NGS data showing the changes in the expression of genes associated with transporters (A) and metabolism (B) related proteins are shown as fold of changes in si-hSMAC-A-TTs relative to si-NT-TTs. (C) The changes in mRNA level (q-PCR) of the genes associated with inflammatory response, redox state regulation (RSR), and exosome are shown.

FIG. 12 depicts that EM and cell membrane network is modified in si-hSMAC-treated tumors: (A, B) Representative electron microscopic image of si-NT and si-hSMAC-A-TTs. Arrows point to lamellar bodies in the si-NT-TTs (A). Black and white arrows point to nuclear membrane and mitochondria, respectively (B).

FIG. 13 is a schematic representation of the effects of SMAC/Diablo depletion on tumor morphology and properties. A schematic presentation of various membrane organelles as ER, Golgi Apparatus, and the endocytic and exocytic membrane dynamics representing intra- and extra-cellular trafficking routes in which the expression of various gens was altered upon silencing of SMAC/Diablo expression.

FIG. 14 demonstrates growth inhibition of the of lung cancer cell line A549 resulted from silencing of SMAC/Diablo using modified si-hSMAC-A (designated A1-A4) or modified si-hSMAC-B (designated B 1-B4) molecules. (A, D) The cells were transfected with each of the indicated si-hSMAC (30 or 50 nM) and 48 h post-transfection, levels of SMAC/Diablo in the cells were evaluated by immunoblotting. β-actin was used as a loading control. (B, E) Quantitative analysis of the immunoblots. (C, F) Growth of the cells transfected with each of the si-hSMAC at the indicated concentration was assayed using the SRB method.

FIG. 15 shows protein interactions of SMAC/Diablo. (A) Network analysis of human proteins interacting with SMAC (B) protein interactions of SMAC/Diablo with glass-bound peptide array consisting of overlapping peptides derived from 14 SMAC/Diablo-interacting proteins. The peptide array was incubated overnight with purified SMAC/Diablo (0.8 μM) and then blotted with anti-SMAC antibodies (1:2000), followed by incubation with HRP-conjugated anti-mouse IgG and detection using a chemiluminescence kit. The black dots indicate SMAC/Diablo binding and the numbers their location on the array, allowing identification of the peptide.

FIG. 16 demonstrates the effect of peptide 2C18 (SEQ ID NO:47) derived from the SMAC/Diablo-interacting protein Ubiquitin conjugating enzyme E2 K Protein (UBEK2) on SMAC/Diablo capability to interact with the 2C18 peptide and additional peptides of the glass-bound peptide array. (A) Peptide array incubated with free SMAC/Diablo as described for FIG. 15 hereinabove. (B) SMAC (0.8 μM) was incubated with the synthetic peptides 2C18 (2.4 μM) and blotted as in (A). The peptide spots that eliminated due to interaction with SMAC/Diablo are circled.

FIG. 17 demonstrates the effect of peptide 1G12 (SEQ ID NO:48) derived from the SMAC/Diablo-interacting protein Baculoviral IAP repeat containing 2 Protein (BIRC2) on SMAC/Diablo capability to interact with the 1G12 peptide and additional peptides of the glass-bound peptide array. (A) Peptide array incubated with free SMAC/Diablo as described for FIG. 15 hereinabove. (B) SMAC (0.8 μM) was incubated with the synthetic peptides derived from BIRC2 spot 1G12 (2.4 μM) blotted as in (A). The peptide spots that eliminated due to interaction with SMAC/Diablo are circled.

FIG. 18 shows that SMAC/Diablo interacts with phosphatidylserine decarboxylase (PSD/PISD). (A) SMAC and PSD purification: lane 1, bacteria extract (Crude ext); lane 2 partially purified PSD (Step 1); lane, 3, purified SMAC; and lane 4, purified PSD (step 2). (B) PSD activity measured by following the formation of phosphatidylethanolamine (PE). (C) PSD binding to SMAC/Diablo using the microscale thermophoresis MST method. (D). A model of mitochondria with proposed SMAC functions in the regulation of PE synthesis at ER-mitochondria contact sites. PS is produced in the ER from PC and PE, and PS then is transferred to the mitochondria, where it is converted by PSD into PE.

DETAILED DESCRIPTION OF THE INVENTION

The present invention addresses the paradox of overexpression of SMAC/Diablo, a protein participating in promoting apoptosis by negatively regulating the inhibitor of apoptosis protein (IAP) family, in several types of cancer. The present invention shows for the first time that silencing SMAC/Diablo expression and/or modulating its activity within the nucleus and/or mitochondria in cancerous cells over-expressing this protein, reduced the proliferation of the cells and/or the growth of tumors comprising cells with the modulated expression and or activity of SMAC/Diablo. According to some embodiments, SMAC/Diablo expression is silenced by RNA inhibitory molecules and its activity within the nucleus and/or mitochondria is modulated using peptides derived with proteins interacting with SMAC/Diablo.

Using as example lung cancer xenografts treated with SMAC/Diablo silencing siRNA molecule, immunohistochemistry and electron-microscopy of residual lung tumor tissue demonstrated morphological changes, including the development of glandular, alveoli-like structures and elimination of lamellar bodies. Next-generation sequencing of lung tumors treated with SMAC/Diablo specific siRNA molecule revealed altered expression of genes associated with intercellular membranal and exosomal networks, cells differentiation, lipid metabolism and transporter expression and/or activity compared to lung tumors treated with non-targeted-siRNA molecule. Silencing of SMAC/Diablo expression decreased phospholipids and phosphatidylcholine levels, and the expression of enzymes associated with their synthesis. Without wishing to be bound by any specific theory or mechanism of action, the above-described phenomena suggest that SMAC/Diablo possesses an additional, non-apoptotic function associated with, inter alia, regulation of lipid synthesis essential for cancer cell growth. Agents inhibiting the expression and/or activity of SMAC/Diablo within the nucleus and/or the mitochondria in cancer types overexpressing this protein can thus be used as therapeutics.

Definitions

As used herein, the terms “SMAC/Diablo” and “SMAC” are used herein interchangeably and refer to the second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI protein. Several SMAC/Diablo variants, generated by alternative splicing, are known in the art, all encompassed within the teachings of the present invention. According to certain embodiments, the terms as used herein refer to a protein having an amino acid sequence at least 80% homologous to the human SMAC/Diablo (hSMAC/Diablo) protein having an amino acids sequence set forth in any one of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO: 6, SEQ ID NO:8 and SEQ ID NO:10. According to certain exemplary embodiments, the terms refers to hSMAC/Diablo protein having an amino acids sequence selected from the group consisting of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO: 6, SEQ ID NO:8 and SEQ ID NO:10.

As used herein, the term “treatment” or “treating” refers to clinical intervention designed to alter the natural course of the individual or cell being treated during the course of clinical pathology, e.g., cancer. Desirable effects of treatment include decreasing the rate of disease progression (delaying progression of a disease), ameliorating or palliating the disease state, and remission or improved prognosis of the disease. For example, an individual is successfully “treated” if one or more symptoms associated with cancer are mitigated or eliminated, including, but are not limited to, reducing the proliferation of cancerous cells, decreasing symptoms resulting from the disease, increasing the quality of life of those suffering from the disease, decreasing the dose of other medications required to treat the disease, delaying the progression of the disease, and/or prolonging survival of individuals.

As used herein, “delaying progression of a disease” means to defer, hinder, slow, retard, stabilize, and/or postpone development of the disease (such as cancer). This delay can be of varying lengths of time, depending on the history of the disease and/or individual being treated. As is evident to one skilled in the art, a sufficient or significant delay can, in effect, encompass prevention, in that the individual does not develop the disease. For example, a late stage cancer, such as development of metastasis, may be delayed.

The terms “cell growth” and “cell proliferation” are used herein interchangeably and refer to the number of viable cells of a particular type observed after a certain growth period.

The terms “inhibit” “decrease”, “reduce” and ‘silence” with regard to the expression or activity of SMAC/Diablo are used herein interchangeably and includes any decrease in expression or protein activity or level of the SMAC/Diablo gene or mRNA or protein encoded by the SMAC/Diablo. According to certain embodiments, inhibition of SMAC/Diablo activity refers to modulation or inhibition of SMAC/Diablo association with partner proteins within the nucleus and/or mitochondria, resulting in an inhibition/decrease/reduction of cell growth (proliferation). The decrease may be of at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 99% or more as compared to the expression of a target gene/mRNA or level of the protein encoded by a gene which has not been targeted by an inhibiting agent and/or as compared to the proliferation rate of cells in which the target gene/mRNA was not silenced or of cells in which the activity of the protein was not modulated.

The terms “polynucleotide”, “nucleic acid sequence”, “polynucleotide sequence” and “oligonucleotide” are used interchangeably herein and refer to an oligomer or polymer of ribonucleic acid (ribo-oligonucleotide or ribo-oligonucleoside) or deoxyribonucleic acid comprising up to about 100-1,000 nucleic acid residues. These terms encompass nucleotide sequences strands composed of naturally-occurring nucleobases, sugars and covalent inter-sugar linkages as well as polynucleotides having non-naturally-occurring portions which function similarly. Such modified or substituted polynucleotides may be preferred over native forms because of the valuable characteristics including, for example, increased stability in the presence of plasma nucleases and enhanced cellular uptake. A polynucleotide may be a polymer of RNA or DNA or hybrid thereof, that is single- or double-stranded, linear or branched, and that optionally contains synthetic, non-natural or altered nucleotide bases. The terms also encompass RNA/DNA hybrids. It is to be explicitly understood that the polynucleotide sequences provided herein can be of DNA or RNA molecules.

“RNA interference (RNAi)” is an evolutionally conserved process whereby the expression or introduction of RNA of a sequence that is identical or highly similar to a target gene results in the sequence specific degradation or specific post-transcriptional gene silencing (PTGS) of messenger RNA (mRNA) transcribed from that targeted gene, thereby inhibiting expression of the target gene. In some embodiments, the RNA is double stranded RNA (dsRNA). This process has been described in plants, invertebrates, and mammalian cells. In nature, RNAi is initiated by the dsRNA-specific endonuclease Dicer, which promotes cleavage of long dsRNA into double-stranded fragments termed siRNAs. siRNAs are incorporated into a protein complex that recognizes and cleaves target mRNAs. RNAi can also be initiated by introducing nucleic acid molecules, e.g., synthetic siRNAs or RNA interfering agents, to inhibit or silence the expression of target genes. As used herein, inhibition by RNAi includes any decrease in expression or protein activity or level of the SMAC/Diablo gene or mRNA or protein encoded by the target gene, i.e., SMAC/Diablo. The decrease may be of at least 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95% or 99% or more as compared to the expression of a target gene or the activity or level of the protein encoded by a target gene which has not been targeted by an RNA interfering agent.

“Small interfering RNA” (siRNA), also referred to herein as “short interfering RNA” is defined as an agent which functions to inhibit expression of a target gene (silencing the gene) e.g., by RNAi. An siRNA may be chemically synthesized, may be produced by in vitro transcription, or may be produced within a host cell. In one embodiment, siRNA is a double stranded RNA (dsRNA) molecule of about 15 to about 40 nucleotides in length, preferably about 15 to about 28 nucleotides, more preferably about 19 to about 25 nucleotides in length, and more preferably about 19, 20, 21, or 22 nucleotides in length, and may contain a 3′ and/or 5′ overhang on each strand having a length of about 0, 1, 2, 3, 4, or 5 nucleotides. The length of the overhang is independent between the two strands, i.e., the length of the overhang on one strand is not dependent on the length of the overhang on the second strand. Preferably the siRNA is capable of promoting RNA interference through degradation or specific post-transcriptional gene silencing (PTGS) of the target messenger RNA (mRNA). According to other embodiment, an siRNA is a small hairpin (also called stem loop) RNA (shRNA). In some embodiments, these shRNAs are composed of a short (e.g., 19-25 nucleotides) antisense strand, followed by a 5-9 nucleotide loop, and the analogous sense strand. Alternatively, the sense strand may precede the nucleotide loop structure and the antisense strand may follow. RNA interfering agents, e.g., siRNA molecules, may be administered to a subject having or at risk for having cancer associated with over-expression of SMAC/Diablo, to inhibit expression of SMAC/Diablo, and thereby treat, ameliorate, or inhibit the cancer in the subject.

The terms “construct”, or “RNAi expression construct” are used herein interchangeably to describe an artificially assembled or isolated nucleic acid molecule which includes the polynucleotide of interest. In general, a construct may include the polynucleotide or polynucleotides of interest, a marker gene which in some cases can also be a gene of interest and appropriate regulatory sequences. According to certain embodiments of the invention, the polynucleotide of interest encode siRNA molecule. It should be appreciated that the inclusion of regulatory sequences in a construct is optional, for example, such sequences may not be required in situations where the regulatory sequences of a host cell are to be used. The regulatory elements typically include a promoter sequence for directing transcription of the polynucleotide of interest in the cell in a constitutive or inducible manner. The term construct includes vectors but should not be seen as being limited thereto. According to certain embodiments, the term “vector,” is intended to refer to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a “plasmid,” which refers to a circular double stranded DNA loop into which additional DNA segments may be ligated. Another type of vector is a phage vector. Another type of vector is a viral vector, wherein additional DNA segments may be ligated into the viral genome (such as an adenoviral vector, a lentiviral vector, etc.). Certain vectors are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (e.g., non-episomal mammalian vectors) can be integrated into the genome of a host cell upon introduction into the host cell and thereby are replicated along with, the host genome.

The terms “complementary” or “complement thereof” are used herein to refer to the sequence of polynucleotide which is capable of forming Watson & Crick base pairing with another specified polynucleotide throughout the entirety of the complementary region. This term is applied to pairs of polynucleotides based solely upon their sequences and not any particular set of conditions under which the two polynucleotides would actually bind. The terms “substantially complementary” and “sufficiently complementary” are used herein interchangeably. An oligomeric compound need not be 100% complementary to its target nucleic acid to be specifically hybridizable. Moreover, an oligomeric compound may hybridize over one or more segments such that intervening or adjacent segments are not involved in the hybridization (e.g., a bulge, a loop structure or a hairpin, structure). A “non-complementary nucleobase” means a nucleobase of an antisense oligonucleotide that is unable to undergo precise base pairing with a nucleobase at a corresponding position in a target nucleic acid. In some embodiments there are non-complementary positions, also known as “mismatches”, between the oligomeric compound and the target nucleic acid, and such non-complementary positions may be tolerated between an oligomeric compound and the target nucleic acid provided that the oligomeric compound remains substantially complementary to the target nucleic acid.

As used herein, the term “peptide” indicates a sequence of amino acids linked by peptide bonds. Peptides according to some embodiments of the present invention consist of 10-50 amino acids, for example 15-35 amino acids or 20-25 amino acids.

In some embodiments, a peptide according to the present invention is up to 30 amino acids, for example up to 29 amino acids, 28 amino acids, 27 amino acids, 26 amino acids, 25 amino acids, 24 amino acids, 23 amino acids, 22 amino acids, 21 amino acids, 20 amino acids, 19 amino acids, 18 amino acids, 17 amino acids, 16 amino acids, 15 amino acids, 14 amino acids, 13 amino acids, 12 amino acids, 11 amino acids, or up to 10 amino acids. Each possibility represents a separate embodiment of the invention.

The term “amino acid” refers to compounds, which have an amino group and a carboxylic acid group, preferably in a 1,2-1,3-, or 1,4-substitution pattern on a carbon backbone. α-Amino acids are most preferred, and include the 20 natural amino acids (which are L-amino acids except for glycine) which are found in proteins, the corresponding D-amino acids, the corresponding N-methyl amino acids, side chain modified amino acids, the biosynthetically available amino acids which are not found in proteins (e.g., 4-hydroxy-proline, 5-hydroxy-lysine, citrulline, ornithine (Orn), canavanine, djenkolic acid, β-cyanoalanine), and synthetically derived α-amino acids, such as aminoisobutyric acid, norleucine (Nle), norvaline (NorVal, Nva), homocysteine and homoserine. β-Alanine and γ-amino butyric acid are examples of 1,3 and 1,4-amino acids, respectively, and many others as well known to the art.

Some of the amino acids used in this invention are those which are available commercially or are available by routine synthetic methods. Certain residues may require special methods for incorporation into the peptide, and either sequential, divergent or convergent synthetic approaches to the peptide sequence are useful in this invention. Natural coded amino acids and their derivatives are represented by one-letter codes or three-letter codes according to IUPAC conventions. When there is no indication, the L isomer was used. The D isomers are indicated by “D” or “(D)” before the residue abbreviation.

As used herein, an “amino acid residue” means the moiety which remains after the amino acid has been conjugated to additional amino acid(s) to form a peptide, or to a moiety (such as a cell penetrating moiety (CPP) and/or mitochondria and/or nucleus targeting moiety), typically through the alpha-amino and carboxyl of the amino acid.

As used herein, the terms “targeting moiety” and “localization moiety” with reference to targeting of a peptide of the invention to the nucleus and/or mitochondria are used herein interchangeably and refer to a molecule which is able to target the peptide to the specific organelle and facilitate or enhance its penetration into the nucleus or mitochondria. The targeting moiety typically enhances the permeability of the peptide, i.e. its ability to penetrate, pervade, or diffuse through a barrier or membrane, typically a phospholipid membrane. The nucleus and/or mitochondria targeting moiety may also enhance the penetration of the peptide through the plasma membrane. Additionally or alternatively, a cell penetrating moiety (CPP) specifically designed to enhance the permeability of the peptide through the plasma membrane is added to the targeting moiety.

The term “expression”, as used herein, refers to the production of a functional end-product e.g., an mRNA or a protein.

According to one aspect, the present invention provides a method for treating or delaying progression of cancer associated with over-expression of second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (SMAC/Diablo) in a subject in need thereof, comprising administering to the subject an effective amount of at least one agent that decreases or inhibits the expression of SMAC/Diablo gene and/or protein and/or modulate the protein activity, and/or its interaction with associated proteins (partners).

According to certain embodiments, the agent that decreases or inhibits the expression and/or activity of SMAC/Diablo is selected from the group consisting of an inhibitory nucleic acid, an inhibitory small molecule, an inhibitory polypeptide or peptide and an inhibitory aptamer.

According to certain aspects, the present invention provides a method for treating or delaying progression of cancer associated with over-expression of second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (SMAC/Diablo) in a subject in need thereof, comprising administering to the subject an effective amount of at least one RNAi molecule, the RNAi molecule comprises a nucleic acid sequence set forth in any one of SEQ ID NOs:12-43.

According to certain embodiments, the method comprises administering an effective amount of an RNAi molecule comprises a nucleic acid sequence set forth in any one of SEQ ID NOs:12-17, 20-25, 28-29, 34-35, and 38-42. Each possibility represents a separate embodiment of the present invention.

Inhibitory Nucleic Acids

According to certain embodiments, the agent is an inhibitory nucleic acid Nucleic acid inhibitors can be used to decrease the expression of SMAC/Diablo gene. Nucleic acid inhibitors include a siRNA, a dsRNA, a ribozyme, a triple-helix former, an aptamer, or an antisense nucleic acid. siRNAs are small double stranded RNAs (dsRNAs) as described hereinabove. Antisense agents can include, for example, from about 8 to about 80 nucleobases (i.e. from about 8 to about 80 nucleotides), e.g., about 8 to about 50 nucleobases, or about 12 to about 30 nucleobases. Antisense compounds include ribozymes, external guide sequence (EGS) oligonucleotides, and other short catalytic RNAs or catalytic oligonucleotides which hybridize to the target nucleic acid and modulate its expression. Antisense compounds can include a stretch of at least eight consecutive nucleobases that are complementary to a sequence in the target gene.

According to certain embodiments, the inhibitory nucleic acid comprises at least 15 consecutive nucleic acids substantially identical to a gene or mRNA at least 80% homologous to the gene or mRNA encoding human SMAC/Diablo (hSMAC/Diablo) protein or to a complementary polynucleotide thereof.

According to certain embodiments, the inhibitory nucleic acid is targeted to a SMAC/Diablo encoding gene comprising a nucleic acid sequence at least 80%, at least 85%, at least 90%, at least 95% or more homologous to the nucleic acid sequence set forth in SEQ ID NO:1 (NG_029459.1).

According to certain embodiments, the hSMAC/Diablo protein is selected from the group consisting of SMAC/Diablo-α, having the amino acid sequence set forth in SEQ ID NO:2; SMAC/Diablo-δ, having the amino acid sequence set forth in SEQ ID NO:4; SMAC/Diablo-β, having the amino acid sequence set forth in SEQ ID NO:6; SMAC/Diablo-4, having the amino acid sequence set forth in SEQ ID NO:8; and SMAC/Diablo-γ, having the amino acid sequence set forth in SEQ ID NO:10. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the hSMAC/Diablo-α is encoded by the nucleic acid sequence having SEQ ID NO:3; hSMAC/Diablo-δ is encoded by the nucleic acid sequence having SEQ ID NO:5; hSMAC/Diablo-β is encoded by the nucleic acid sequence having SEQ ID NO:7; hSMAC/Diablo-4 is encoded by the nucleic acid sequence having SEQ ID NO:9; and hSMAC/Diablo-γ is encoded by the nucleic acid sequence having SEQ ID NO:11. Each possibility represents a separate embodiment of the present invention.

The nucleic acid agents of the present invention are of at least 10, at least 11, at least 12, at least 13, at least 14, at least 15, at least 16, at least 17 at least 18, at least 19, at least 20, or at least 21 bases specifically hybridizable with SMAC/Diablo RNA, but excluding the full length SMAC/Diablo transcript or known variants thereof. The SMAC/Diablo-silencing oligonucleotides of the invention are preferably no more than about 1000 bases in length, more preferably no more than about 100 bases in length. In other preferable embodiments, the oligonucleotides are no more than 30 nucleotides (or base pairs) in length.

According to certain embodiments, the RNAi molecule comprises a nucleic acid sequence selected from the group consisting of SEQ ID NO:12-43.

According to certain exemplary embodiments, the SMAC/Diablo inhibitory nucleic acid is siRNA molecule selected from the group consisting of:

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:12 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:13;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:14 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:15;

siRNA comprising a first sense strand having the nucleic acid sequence set forth in SEQ ID NO:16 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:17; and

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:18 and second polynucleotide having the nucleic acid sequence set forth in SEQ ID NO:19.

According to certain embodiments, the hSMAC/Diablo protein is hSMAC/Diablo-β having the amino acid sequence set forth in SEQ ID NO:6, encoded by the nucleic acid sequence set forth in NO:7. According to these embodiments, wherein the inhibitory nucleic acid is siRNA molecule, the siRNA molecule is selected from the group consisting of siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:22 and second polynucleotide having the nucleic acid sequence set forth in SEQ ID NO:23; siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:24 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:25; and siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:26 and an anti sense strand having the nucleic acid sequence set forth in SEQ ID NO:27.

According to certain embodiments, the hSMAC/Diablo protein is hSMAC/Diablo-δ having the amino acid sequence set forth in SEQ ID NO:4, encoded by the nucleic acid sequence set forth in SEQ ID NO:5. According to these embodiments, wherein the inhibitory nucleic acid is siRNA molecule, the siRNA molecule is selected from the group consisting of siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:20 and an anti sense strand having the nucleic acid sequence set forth in SEQ ID NO:21; siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:22 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:23; and siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:24 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:25.

According to certain embodiments, the hSMAC/Diablo protein is hSMAC/Diablo-4 having the amino acid sequence set forth in SEQ ID NO:8, encoded by the nucleic acid sequence set forth in SEQ ID NO:9. According to these embodiments, wherein the inhibitory nucleic acid is siRNA molecule, the siRNA molecule is selected from the group consisting of siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:22 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:23; siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:24 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:25; and siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:26 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:27.

According to certain embodiments, the hSMAC/Diablo protein is hSMAC/Diablo-γ having the amino acid sequence set forth in SEQ ID NO:10, encoded by the nucleic acid sequence set forth in SEQ ID NO:11. According to these embodiments, wherein the inhibitory nucleic acid is siRNA molecule, the siRNA molecule is selected from the group consisting of siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:22 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:23; and siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:24 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:25.

In some embodiments, the sense and antisense strands of the present siRNA can comprise two complementary, single-stranded RNA molecules or can comprise a single molecule in which two complementary portions are base-paired and are covalently linked by a single-stranded “hairpin” area. Without wishing to be bound by any theory, it is believed that the hairpin area of the latter type of siRNA molecule is cleaved intracellularly by the “Dicer” protein (or its equivalent) to form a siRNA of two individual base-paired RNA molecules.

Preferably, one or both strands of the siRNA of the invention can also comprise a 3′ overhang. As used herein, a “3′ overhang” refers to at least one unpaired nucleotide extending from the 3′-end of an RNA strand. Thus in one embodiment, the siRNA of the invention comprises at least one 3′ overhang of from 1 to about 6 nucleotides (which includes ribonucleotides or deoxynucleotides) in length, from 1 to about 5 nucleotides in length, from 1 to about 4 nucleotides in length, or from about 2 to about 4 nucleotides in length. In the embodiment in which both strands of the siRNA molecule comprise a 3′ overhang, the length of the overhangs can be the same or different for each strand. In a most preferred embodiment, the 3′ overhang is present on both strands of the siRNA, and is 2 nucleotides in length. For example, each strand of the siRNA of the invention can comprise 3′ overhangs of dithymidylic acid (“TT”) or diuridylic acid (“UU”).

As illustrated in the Example section hereinbelow, exemplary siRNA oligonucleotides of the present invention are 19 to 21 base pairs in length with two 3′ overhang on each strand, selected from the group consisting of:

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:20 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:21;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:22 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:23;

siRNA comprising a first sense strand having the nucleic acid sequence set forth in SEQ ID NO:24 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:25; and

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:26 and second polynucleotide having the nucleic acid sequence set forth in SEQ ID NO:27.

While a preferable embodiment of the invention is directed to double-stranded siRNA molecules wherein the two 3′ nucleotides are deoxythymidine residues (SEQ ID Nos. 20-27), it is to be understood that other modifications are within the scope of the present invention. Thus, the use of analogs, variants and derivatives of the sequences set forth in any one of SEQ ID NOS: 12-27 is contemplated, as long as the inhibitory activity of the SMAC/Diablo expression is retained. For example, in a particular embodiment, the siRNA may contain 2′-O-methyl and/or phosphorothioate substituent nucleotides. According to certain exemplary embodiments, the siRNA may contain 2′-O-methyl (2′-O-ME) modification. According to these embodiments, the siRNA is selected from the group consisting of siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:28 and an antisense strand having the nucleic acid sequence set forth in SEQ ID N0:29; siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:30 and an antisense strand having the nucleic acid sequence set forth in SEQ ID N0:31; siRNA comprising a first sense strand having the nucleic acid sequence set forth in SEQ ID NO:32 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:33; siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:34 and second polynucleotide having the nucleic acid sequence set forth in SEQ ID NO:35; siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:36 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:37; siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:38 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:39; siRNA comprising a first sense strand having the nucleic acid sequence set forth in SEQ ID NO:40 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:41; and siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:42 and second polynucleotide having the nucleic acid sequence set forth in SEQ ID NO:43.

In other particular embodiments, the siRNA is a variant, homolog or derivative of any one of SEQ ID NOs:12-27.

As used herein, the term “variant” refers to substantially similar sequences possessing common qualitative biological activities. An oligonucleotide variant includes a pharmaceutically acceptable salt, homolog, analog, extension or fragment of a nucleotide sequence useful for the invention. Encompassed within the term “variant” are chemically modified natural and synthetic nucleotide molecules (derivatives). Also encompassed within the term “variant” are substitutions, additions or deletions within the nucleotide sequence of the molecule, as long as the required function is sufficiently maintained. Oligonucleotide variants may share at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity (homology). In different embodiments, “homolog” may refer e.g. to any degree of homology disclosed herein.

Another agent capable of silencing the expression of a SMAC/Diablo RNA is a DNAzyme molecule capable of specifically cleaving its encoding polynucleotides. DNAzymes are single-stranded nucleic acid agents which are capable of cleaving both single and double stranded target sequences. A general model (the “10-23” model) for the DNAzyme has been proposed. “10-23” DNAzymes have a catalytic domain of 15 deoxyribonucleotides, flanked by two substrate-recognition domains of seven to nine deoxyribonucleotides each. This type of DNAzyme can effectively cleave its substrate RNA at purine:pyrimidine junctions (for a review of DNAzymes see Khachigian, L. M. 2002. Curr Opin Mol Ther 4, 119-21). Examples of construction and amplification of synthetic, engineered DNAzymes recognizing single and double-stranded target cleavage sites have been disclosed in U.S. Pat. No. 6,326,174.

Another agent capable of silencing SMAC/Diablo is a ribozyme molecule capable of specifically cleaving its encoding polynucleotides. Ribozymes are being increasingly used for the sequence-specific inhibition of gene expression by the cleavage of mRNAs encoding proteins of interest (Welch et al., 1998. Curr Opin Biotechnol. 9:486-96). The possibility of designing ribozymes to cleave any specific target RNA has rendered them valuable tools in both basic research and therapeutic applications. In the therapeutics area, ribozymes have been exploited to target viral RNAs in infectious diseases, dominant oncogenes in cancers and specific somatic mutations in genetic disorders. Most notably, several ribozyme gene therapy protocols for HIV patients are already in Phase 1 trials. More recently, ribozymes have been used for transgenic animal research, gene target validation and pathway elucidation. Several ribozymes are in various stages of clinical trials. ANGIOZYME was the first chemically synthesized ribozyme to be studied in human clinical trials. ANGIOZYME specifically inhibits formation of the VEGF-r (Vascular Endothelial Growth Factor receptor), a key component in the angiogenesis pathway. Ribozyme Pharmaceuticals, Inc., as well as other firms has demonstrated the importance of anti-angiogenesis therapeutics in animal models. HEPTAZYME, a ribozyme designed to selectively destroy Hepatitis C Virus (HCV) RNA, was found effective in decreasing Hepatitis C viral RNA in cell culture assays (Ribozyme Pharmaceuticals, Incorporated—http://www.rpi.com/index.html).

An additional method of silencing SMAC/Diablo is via triplex forming oligonucleotides (TFOs). In the last decade, studies have shown that TFOs can be designed which can recognize and bind to polypurine/polypirimidine regions in double-stranded helical DNA in a sequence-specific manner. Thus the DNA sequence encoding the SMAC/Diablo RNA of the present invention can be targeted thereby down-regulating the RNA molecule.

The recognition rules governing TFOs are outlined e.g. by EP Publication 375408. Modification of the oligonucleotides, such as the introduction of intercalators and backbone substitutions, and optimization of binding conditions (pH and cation concentration) have aided in overcoming inherent obstacles to TFO activity such as charge repulsion and instability, and it was recently shown that synthetic oligonucleotides can be targeted to specific sequences (for a recent review see Seidman and Glazer, 2003. J Clin Invest; 112:487-94).

In general, the triplex-forming oligonucleotide has the sequence correspondence:

oligo 3'--A G G T duplex 5'--A G C T duplex 3'--T C G A However, it has been shown that the A-AT and G-GC triplets have the greatest triple helical stability. The same authors have demonstrated that TFOs designed according to the A-AT and G-GC rule do not form non-specific triplexes, indicating that the triplex formation is indeed sequence specific.

Thus for any given sequence in the regulatory region a triplex forming sequence may be devised. Triplex-forming oligonucleotides preferably are at least 15, more preferably 25, still more preferably 30 or more nucleotides in length, up to 50 or 100 bp.

Transfection of cells (for example, via cationic liposomes) with TFOs, and subsequent formation of the triple helical structure with the target DNA, induces steric and functional changes, blocking transcription initiation and elongation, allowing the introduction of desired sequence changes in the endogenous DNA and results in the specific downregulation of gene expression. In addition, Vuyisich and Beal have recently shown that sequence specific TFOs can bind to dsRNA, inhibiting activity of dsRNA-dependent enzymes such as RNA-dependent kinases (Vuyisich and Beal, 2000. Nuc. Acids Res 28:2369-74). Additionally, TFOs designed according to the abovementioned principles can induce directed mutagenesis capable of effecting DNA repair, thus providing both downregulation and upregulation of expression of endogenous genes (Seidman and Glazer, 2003, ibid). Detailed description of the design, synthesis and administration of effective TFOs can be found in U.S. Patent Application Nos. 2003/017068; 2003/0096980; 2002/0128218 and 2002/0123476 and U.S. Pat. No. 5,721,138.

It will be appreciated that nucleic acid agents capable of hybridizing SMAC/Diablo RNA may down-regulate an activity thereof by preventing SMAC/Diablo RNA binding to another downstream agent.

The inhibitory acid agents of the present invention (e.g., an siRNA molecule such as those set forth by any one of SEQ ID NOs:12-27) can be directly administered to the subject or can be expressed within the subject cell. To express such an agent (i.e., to produce an RNA molecule) in mammalian cells, a nucleic acid sequence encoding the agents of the present invention is preferably ligated into a nucleic acid construct suitable for mammalian cell expression. Such a nucleic acid construct includes a promoter sequence and additional regulatory elements for directing transcription of the polynucleotide sequence in the cell in a constitutive or inducible manner. The nucleic acid construct may preferably include additional sequences to form an expression vector suitable for replication and/or integration in eukaryotes, and preferably also in prokaryotes.

The type of vector may be selected e.g. for producing single-stranded or double-stranded RNA or DNA. Suitable vectors for producing various silencing oligonucleic acids are known in the art. For example, RNAi expression vectors (also referred to as a dsRNA-encoding plasmid) are replicable nucleic acid constructs used to express (transcribe) RNA which produces siRNA moieties in the cell in which the construct is expressed. Such vectors include a transcriptional unit comprising an assembly of (1) genetic element(s) having a regulatory role in gene expression, for example, promoters, operators, or enhancers, operatively linked to (2) a “coding” sequence which is transcribed to produce a double-stranded RNA (two RNA moieties that anneal in the cell to form an siRNA, or a single hairpin RNA which can be processed to an siRNA), and (3) appropriate transcription initiation and termination sequences.

Some of these vectors have been engineered to express small hairpin RNAs (shRNAs), which get processed in vivo into siRNA-like molecules capable of carrying out gene-specific silencing. Another type of siRNA expression vector encodes the sense and antisense siRNA strands under control of separate pol III promoters. The siRNA strands from this vector, like the shRNAs of the other vectors, have 3′ thymidine termination signals. Silencing efficacy by both types of expression vectors was comparable to that induced by transiently transfecting siRNA.

Expression vectors containing regulatory elements from eukaryotic viruses such as retroviruses can be also used.

Various vectors for delivering and expressing silencing RNA molecules such as siRNAs are known in the art, and include for example plasmid vectors, inducible vectors, adenoviral vectors, retroviral vectors and lentiviral vectors and CMV-based vectors. Exemplary vectors include pSilencer™ vectors (Ambion), Genescript siRNA vectors, Imagenex vectors (e.g. IMG-1000, IMG-700 and IMG-1200), among others.

Various methods can be used to introduce the expression vector of the present invention into cells. Such methods are generally described in Sambrook et al, (1989, 1992), in Ausubel et al., (1989), Chang et al., (1995), Vega et al., (1995), and Gilboa et at. (1986), and include, for example, stable or transient transfection, lipofection, electroporation and infection with recombinant viral vectors. In addition, see U.S. Pat. Nos. 5,464,764 and 5,487,992 for positive-negative selection methods.

Useful lipids for lipid-mediated transfer of the RNA inhibitory molecule of the invention or construct comprising same are, for example, DOTMA, DOPE, and DC-Chol (Tonkinson et al., 1996. Cancer Investigation, 14(1): 54-65). Other vectors can be used, such as cationic lipids, polylysine, and dendrimers.

Other than containing the necessary elements for the transcription of the inserted coding sequence, the expression construct of the present invention can also include sequences engineered to enhance stability, production, purification, yield or toxicity of the expressed RNA.

According to another aspect, the present invention provides an isolated SMAC/Diablo silencing molecule selected from the group consisting of:

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:14 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:15;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:16 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:17;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:18 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:19;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:22 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:23;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:24 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:25;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:26 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:27;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:28 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:29;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:30 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:31;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:32 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:33;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:34 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:35;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:36 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:37;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:38 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:39;

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:40 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:41; and

siRNA comprising a sense strand having the nucleic acid sequence set forth in SEQ ID NO:42 and an antisense strand having the nucleic acid sequence set forth in SEQ ID NO:43. Each possibility represents a separate embodiment of the present invention.

According to certain aspects, the present invention provides a method for treating or delaying progression of cancer associated with over-expression of second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (SMAC/Diablo) in a subject in need thereof, comprising administering to the subject an effective amount of at least one peptide conjugate comprising a peptide derived from SMAC/Diablo-interacting protein having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and a mitochondria and/or nucleus targeting moiety.

According to certain embodiments, the method comprises administering an effective amount of a peptide conjugate comprising the amino acid sequence set forth in any one of SEQ ID NOs:69-71 and 73-74. Each possibility represents a separate embodiment of the present invention.

Inhibitory Peptides

The present invention discloses novel peptides derived from proteins that interact with SMAC/Diablo. When the peptide derived from SMAC/Diablo-interacting protein is targeted into the cell and further into the nucleus and/or the mitochondria, such that the interaction with hSMAC/Diablo occurs within the organelle(s), the interaction results in inhibition or intervention with at least one of phospholipid biosynthesis, cell growth, cell proliferation and any combination thereof.

According to further embodiments of the invention, the agent that inhibits the activity of SMAC/Diablo is an inhibitory peptide targeted to the nucleus and/or to the mitochondria of a cell overexpressing SMAC/Diablo.

According to certain embodiments, the inhibiting molecule is a peptide conjugate comprising a peptide derived from SMAC/Diablo-interacting protein having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and a mitochondria and/or nucleus targeting moiety. The mitochondria and/or nucleus targeting moiety can be peptidic or non-peptidic, and is covalently linked to the peptide derived from SMAC/Diablo-interacting protein directly or via linker. The targeting moiety may be linked to the peptide derived from SMAC/Diablo-interacting protein at any position. According to some embodiments, the targeting moiety is linked to the N- or the C-terminus of the peptide derived from SMAC/Diablo-interacting protein. When the conjugate comprises a combination of mitochondria and nucleus targeting moieties each moiety may be independently linked to the N- or C-terminus of the peptide or the mitochondria and nucleus targeting moieties can be linked in tandem to the N- or C-terminus of the peptide. According to certain exemplary embodiments, each of the nucleus and mitochondria targeting moiety also enhances the permeability of the peptide conjugate through the cell membrane.

The peptides derived from SMAC/Diablo-interacting proteins and/or the peptide conjugate can be synthetic or recombinant.

According to certain embodiments, the nucleus and/or mitochondria targeting moiety enhances the permeability of the peptide derived from SMAC/Diablo-interacting protein through the nuclear or mitochondrial membrane, respectively, and typically also through the cell membrane.

According to certain embodiments, the C-terminus of the peptide conjugate is a modified carboxy terminal group selected from the group consisting of an amide, ester and alcohol group. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the peptide conjugate comprises a peptide derived from hSMAC/Diablo-interacting protein having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and a nucleus targeting moiety.

According to certain embodiments, the peptide conjugate comprises a peptide derived from hSMAC/Diablo-interacting protein having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and a mitochondria targeting moiety.

According to some embodiments, the peptide conjugate comprises an amino acid sequence selected from the group consisting of SEQ ID NO:69; SEQ ID NO:70; SEQ ID NO:71; SEQ ID NO:73; and SEQ ID NO:74. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the peptide conjugate further comprises at least one additional moiety selected from the group consisting of cell penetration moiety, a detectable label and a carrier. Each possibility represents a separate embodiment of the present invention. In some embodiments, the cell penetration moiety is a fatty acid residue. The additional moiety can be linked to the peptide conjugate directly or via a linker. Each possibility represents a separate embodiment of the present invention.

According to some embodiments, the conjugated peptides of the present invention comprise a cell penetrating moiety.

In some embodiments, the amino terminus of the peptides disclosed herein is modified. In some embodiments, the amino terminal modification is addition of a cell penetration moiety.

In some embodiments, the carboxy terminus of the conjugated peptides disclosed herein is modified. In some embodiments, the carboxy terminal modification is addition of a permeability-enhancing moiety.

Non-limitative examples of cell permeability moieties include hydrophobic moieties such as lipids, fatty acids, steroids and bulky aromatic or aliphatic compounds. According to certain embodiments, the cell penetrating moiety is a peptide (CPP).

In some embodiments, the cell permeability moiety is covalently linked to the N- or C-terminus of the peptide conjugate via a direct bond. In other embodiments, the cell permeability moiety is covalently linked to the N- or C-terminus of the peptide via a linker. In some embodiments, the cell permeability moiety is a fatty acid residue. In some embodiments, the fatty acid residue is selected from C12-C20 fatty acids. In some particular embodiments, the fatty acid residue is a myristoyl group (Myr). In additional particular embodiments, the fatty acid residue is a stearoyl group (Stear). In yet additional embodiments, the fatty acid residue is a palmitoyl group (Palm).

In some embodiments, the peptide-conjugate amino terminus is modified with an amino terminal blocking group. In some embodiments, the amino terminal blocking group is selected from the group consisting of an acetyl and alkyl. Each possibility represents a separate embodiment of the present invention.

In some embodiments, the carboxy terminus of the peptide conjugates disclosed herein is modified. In some embodiments, the carboxy terminus is modified with a carboxy terminal group. In some embodiments, the carboxy terminal group is selected from the group consisting of amide, ester and alcohol group. Each possibility represents a separate embodiment of the present invention. In some particular embodiments, the carboxy terminal group is an amide group.

The procedures utilized to construct peptide compounds of the present invention generally rely on the known principles and methods of peptide synthesis, such as solid phase peptide synthesis, partial solid phase synthesis, fragment condensation and classical solution synthesis.

Some of the peptides of the present invention, that do not comprise non-coded amino acids, can be synthesized using recombinant methods know in the art. Peptide conjugates may be synthesized chemically or alternatively may be produced recombinantly and coupled synthetically with the conjugating moiety.

The peptides of the invention can be used in the form of pharmaceutically acceptable salts. As used herein the term “salts” refers to both salts of carboxyl groups and to acid addition salts of amino or guanido groups of the peptide molecule. The term “pharmaceutically acceptable” means suitable for administration to a subject, e.g., a human. For example, the term “pharmaceutically acceptable” can mean approved by a regulatory agency of the Federal or a state government or listed in the U. S. Pharmacopeia or other generally recognized pharmacopeia for use in animals, and more particularly in humans. Pharmaceutically acceptable salts include those salts formed with free amino groups such as salts derived from non-toxic inorganic or organic acids such as acetic acid, citric acid or oxalic acid and the like, and those salts formed with free carboxyl groups such as salts derived from non-toxic inorganic or organic bases such as sodium, calcium, potassium, ammonium, calcium, ferric or zinc, isopropylamine, triethylamine, procaine, and the like.

Analogs and derivatives of the peptides are also within the scope of the present application.

“Derivatives” of the peptides of the invention as used herein cover derivatives which may be prepared from the functional groups which occur as side chains on the residues or the N- or C-terminal groups, by means known in the art, and are included in the invention as long as they remain pharmaceutically acceptable, i.e., they do not destroy the activity of the peptide, do not confer toxic properties on compositions containing it, and do not adversely affect the immunogenic properties thereof.

These derivatives may include, for example, aliphatic esters of the carboxyl groups, amides of the carboxyl groups produced by reaction with ammonia or with primary or secondary amines, N-acyl derivatives of free amino groups of the amino acid residues, e.g., N-acetyl, formed by reaction with acyl moieties (e.g., alkanoyl or carbocyclic aroyl groups), or 0-acyl derivatives of free hydroxyl group (e.g., that of seryl or threonyl residues) formed by reaction with acyl moieties.

“Analogs” of the peptides of the invention as used herein cover compounds which have the amino acid sequence according to the invention except for one or more amino acid changes, typically, conservative amino acid substitutions.

In some embodiments, an analog has at least about 75% identity to the sequence of the peptide of the invention, for example at least about 80%, at least about 85%, at least about 90%, at least about 99% identity to the sequence of the peptide of the invention.

Conservative substitutions of amino acids as known to those skilled in the art are within the scope of the present invention. Conservative amino acid substitutions include replacement of one amino acid with another having the same type of functional group or side chain e.g. aliphatic, aromatic, positively charged, negatively charged.

Conservative substitution tables providing functionally similar amino acids are well known in the art.

The following six groups each contain amino acids that are conservative substitutions for one another:

1) Alanine (A), Serine (S), Threonine (T);

2) Aspartic acid (D), Glutamic acid (E);

3) Asparagine (N), Glutamine (Q);

4) Arginine (R), Lysine (K), Histidine (H);

5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V); and

6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W).

Analogs according to the present invention may comprise also peptidomimetics. “Peptidomimetic” means that a peptide according to the invention is modified in such a way that it includes at least one non-coded residue or non-peptidic bond. Such modifications include, e.g., alkylation and more specific methylation of one or more residues, insertion of or replacement of natural amino acid by non-natural amino acids, replacement of an amide bond with another covalent bond. A peptidomimetic according to the present invention may optionally comprise at least one bond which is an amide replacement bond such as urea bond, carbamate bond, sulfonamide bond, hydrazine bond, or any other covalent bond. The design of appropriate analogs may be computer assisted. Analogs are included in the invention as long as they remain pharmaceutically acceptable and their activity is not damaged.

The inhibitory agents of the present invention can be administered to a subject per se, or in a pharmaceutical composition where they are mixed with suitable carriers or excipients.

According to yet additional aspect, the present invention provides an isolated synthetic or recombinant peptide having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, an analog, derivative or a fragment thereof, wherein the peptide is capable of binding to human SMAC/Diablo. According to certain embodiments, the peptide comprises the amino acid sequence set forth in any one of SEQ ID NOs:46-67. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the peptide further comprises a nucleus and/or mitochondria targeting moiety. The nucleus or mitochondria targeting moiety can be linked to the peptide at any position, typically at the N- or at the C-terminus, directly or via a linker. According to some embodiments, the conjugate further comprises a cell-penetrating moiety.

According to certain embodiments, the present invention provides a synthetic or recombinant peptide having the amino acid sequence set forth in SEQ ID NO:69.

According to certain embodiments, the present invention provides a synthetic or recombinant peptide having the amino acid sequence set forth in SEQ ID NO:70.

According to certain embodiments, the present invention provides a synthetic or recombinant peptide having the amino acid sequence set forth in SEQ ID NO:71.

According to certain embodiments, the present invention provides a synthetic or recombinant peptide having the amino acid sequence set forth in SEQ ID NO:73.

According to certain embodiments, the present invention provides a synthetic or recombinant peptide having the amino acid sequence set forth in SEQ ID NO:74.

Pharmaceutical Compositions

The agents of the present invention can be administered to a subject per se, or in a pharmaceutical composition where they are mixed with suitable carriers or excipients.

As used herein a “pharmaceutical composition” refers to a preparation of one or more of the active ingredients described herein with other chemical components such as physiologically suitable carriers and excipients. The purpose of a pharmaceutical composition is to facilitate administration of a compound to an organism.

Herein the term “active ingredient” refers to the agent accounting for silencing the expression of SMAC/Diablo and/or modulating its activity within a nucleus or mitochondria of a cancerous cell overexpressing SMAC/Diablo. According to certain exemplary embodiments, the active ingredient of the invention inhibits the proliferation of cancerous cell and/or reduces the growth of a tumor in cancers wherein SMAC/Diablo is overexpressed.

Hereinafter, the phrases “physiologically acceptable carrier” and “pharmaceutically acceptable carrier” which may be interchangeably used refer to a carrier or a diluent that does not cause significant irritation to an organism and does not abrogate the biological activity and properties of the administered compound.

Herein the term “excipient” refers to an inert substance added to a pharmaceutical composition to further facilitate administration of an active ingredient. Examples, without limitation, of excipients include calcium carbonate, calcium phosphate, various sugars and types of starch, cellulose derivatives, gelatin, vegetable oils and polyethylene glycols.

Techniques for formulation and administration of drugs may be found in “Remington's Pharmaceutical Sciences,” Mack Publishing Co., Easton, Pa., latest edition, which is incorporated herein by reference.

Suitable routes of administration may, for example, include oral, rectal, transmucosal, especially transnasal, intestinal or parenteral delivery, including intramuscular, subcutaneous and intramedullary injections as well as intrathecal, direct intraventricular, intravenous, inrtaperitoneal, or intranasal injections.

Alternately, one may administer the pharmaceutical composition in a local rather than systemic manner, for example, by intra-articular injections or by microinjections, under arthroscopy, into the inflammatory synovial tissue (i.e. in situ).

Pharmaceutical compositions of the present invention may be manufactured by processes well known in the art, e.g., by means of conventional mixing, dissolving, granulating, dragee-making, levigating, emulsifying, encapsulating, entrapping or lyophilizing processes.

Pharmaceutical compositions for use in accordance with the present invention thus may be formulated in conventional manner using one or more physiologically acceptable carriers comprising excipients and auxiliaries, which facilitate processing of the active ingredients into preparations which can be used pharmaceutically. Proper formulation is dependent upon the route of administration chosen.

For injection, the active ingredients of the pharmaceutical composition may be formulated in aqueous solutions, preferably in physiologically compatible buffers such as Hank's solution, Ringer's solution, or physiological salt buffer. For transmucosal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art.

For oral administration, the pharmaceutical composition can be formulated readily by combining the active compounds with pharmaceutically acceptable carriers well known in the art. Such carriers enable the pharmaceutical composition to be formulated as tablets, pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions, and the like, for oral ingestion by a patient. Pharmacological preparations for oral use can be made using a solid excipient, optionally grinding the resulting mixture, and processing the mixture of granules, after adding suitable auxiliaries if desired, to obtain tablets or dragee cores. Suitable excipients are, in particular, fillers such as sugars, including lactose, sucrose, mannitol, or sorbitol; cellulose preparations such as, for example, maize starch, wheat starch, rice starch, potato starch, gelatin, gum tragacanth, methyl cellulose, hydroxypropylmethyl-cellulose, sodium carbomethylcellulose; and/or physiologically acceptable polymers such as polyvinylpyrrolidone (PVP). If desired, disintegrating agents may be added, such as cross-linked polyvinyl pyrrolidone, agar, or alginic acid or a salt thereof such as sodium alginate.

Dragee cores are provided with suitable coatings. For this purpose, concentrated sugar solutions may be used which may optionally contain gum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethylene glycol, titanium dioxide, lacquer solutions and suitable organic solvents or solvent mixtures. Dyestuffs or pigments may be added to the tablets or dragee coatings for identification or to characterize different combinations of active compound doses.

Pharmaceutical compositions which can be used orally include push-fit capsules made of gelatin as well as soft, sealed capsules made of gelatin and a plasticizer, such as glycerol or sorbitol. The push-fit capsules may contain the active ingredients in admixture with filler such as lactose, binders such as starches, lubricants such as talc or magnesium stearate and, optionally, stabilizers. In soft capsules, the active ingredients may be dissolved or suspended in suitable liquids, such as fatty oils, liquid paraffin, or liquid polyethylene glycols. In addition, stabilizers may be added. All formulations for oral administration should be in dosages suitable for the chosen route of administration.

For buccal administration, the compositions may take the form of tablets or lozenges formulated in conventional manner.

For administration by nasal inhalation, the active ingredients for use according to the present invention are conveniently delivered in the form of an aerosol spray presentation from a pressurized pack or a nebulizer with the use of a suitable propellant, e.g., dichlorodifluoromethane, trichlorofluoromethane, dichloro-tetrafluoroethane or carbon dioxide. In the case of a pressurized aerosol, the dosage unit may be determined by providing a valve to deliver a metered amount. Capsules and cartridges of, e.g., gelatin for use in a dispenser may be formulated containing a powder mix of the compound and a suitable powder base such as lactose or starch.

The pharmaceutical composition described herein may be formulated for parenteral administration, e.g., by bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form, e.g., in ampoules or in multidose containers with optionally, an added preservative. The compositions may be suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilizing and/or dispersing agents.

Pharmaceutical compositions for parenteral administration include aqueous solutions of the active preparation in water-soluble form. Additionally, suspensions of the active ingredients may be prepared as appropriate oily or water based injection suspensions. Suitable lipophilic solvents or vehicles include fatty oils such as sesame oil, or synthetic fatty acids esters such as ethyl oleate, triglycerides or liposomes. Aqueous injection suspensions may contain substances, which increase the viscosity of the suspension, such as sodium carboxymethyl cellulose, sorbitol or dextran. Optionally, the suspension may also contain suitable stabilizers or agents which increase the solubility of the active ingredients to allow for the preparation of highly concentrated solutions.

Alternatively, the active ingredient may be in powder form for constitution with a suitable vehicle, e.g., sterile, pyrogen-free water based solution, before use.

The pharmaceutical composition of the present invention may also be formulated in rectal compositions such as suppositories or retention enemas, using, e.g., conventional suppository bases such as cocoa butter or other glycerides.

Preferably the pharmaceutical composition can also include DOTMA, DOPE, and DC-Chol (Tonkinson et al., 1996, ibid) as transfection agents or as additives to transfection agents neutralizing the negative charge of the nucleotides in the RNA inhibiting molecules. A preferred example of a transfection agent is poly(ethylamine) (PEI).

Pharmaceutical compositions suitable for use in context of the present invention include compositions wherein the active ingredients are contained in an amount effective to achieve the intended purpose. More specifically, a therapeutically effective amount means an amount of active ingredients (nucleic acid agent) effective to prevent, alleviate or ameliorate symptoms of a disorder or prolong the survival of the subject being treated.

Determination of a therapeutically effective amount is well within the capability of those skilled in the art, especially in light of the detailed disclosure provided herein.

For any preparation used in the methods of the invention, the therapeutically effective amount or dose can be estimated initially from in vitro and cell culture assays. For example, a dose can be formulated in animal models to achieve a desired concentration or titer. Such information can be used to more accurately determine useful doses in humans.

Toxicity and therapeutic efficacy of the active ingredients described herein can be determined by standard pharmaceutical procedures in vitro, in cell cultures or experimental animals. The data obtained from these in vitro and cell culture assays and animal studies can be used in formulating a range of dosage for use in human. The dosage may vary depending upon the dosage form employed and the route of administration utilized. The exact formulation, route of administration and dosage can be chosen by the individual physician in view of the patient's condition. (See e.g., Fingl, et al., 1975. In: “The Pharmacological Basis of Therapeutics”, Ch. 1 p. 1).

Dosage amount and interval may be adjusted individually to provide plasma levels of the active ingredient are sufficient to induce or suppress the biological effect (minimal effective concentration, MEC). The MEC will vary for each preparation, but can be estimated from in vitro data. Dosages necessary to achieve the MEC will depend on individual characteristics and route of administration. Detection assays can be used to determine plasma concentrations.

Depending on the severity and responsiveness of the condition to be treated, dosing can be of a single or a plurality of administrations, with course of treatment lasting from several days to several weeks or until cure is effected or diminution of the disease state is achieved.

The amount of a composition to be administered will, of course, be dependent on the subject being treated, the severity of the affliction, the manner of administration, the judgment of the prescribing physician, etc.

Compositions of the present invention may, if desired, be presented in a pack or dispenser device, such as the U.S. Food and Drug Administration (FDA) approved kit, which may contain one or more unit dosage forms containing the active ingredient. The pack may, for example, comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be accompanied by instructions for administration. The pack or dispenser may also be accommodated by a notice associated with the container in a form prescribed by a governmental agency regulating the manufacture, use or sale of pharmaceuticals, which notice is reflective of approval by the agency of the form of the compositions or human or veterinary administration. Such notice, for example, may be of labeling approved by the U.S. Food and Drug Administration for prescription drugs or of an approved product insert. Compositions comprising a preparation of the invention formulated in a compatible pharmaceutical carrier may also be prepared, placed in an appropriate container, and labeled for treatment of an indicated condition, as if further detailed above.

The present invention demonstrates over-expression of SMAC/Diablo in many types of cancer, additional to those reported in other studies (Bao, S. T., et al., 2006, ibid; Arellano-Llamas, A., et al., 2006, ibid; Yoo, N. J., et al., 2003, ibid; Shintani, M., et al., 2014 ibid; Kempkensteffen, C., et al., 2008, ibid; and Shibata, T., et al., 2007. Diagn Mol Pathol 16, 1-8). This is unexpected in view of the pro-apoptotic activity of the protein, which promotes caspase activation by binding IAPB. The present invention demonstrates that silencing SMAC/Diablo expression in various cancer cell lines over-expressing SMAC/Diablo inhibited their growth, and, furthermore, in lung cancer xenografts inhibited tumor growth and resulted in the formation of glandular alveoli-like structures, and morphological changes indicative of cell differentiation. Cell growth inhibition was not observed in non-cancerous cell lines, although SMAC/Diablo expression was inhibited. Inhibition of the cancer-cell growth as a result of SMAC/Diablo silencing, but not in non-cancerous cells, implies for an important functional role of the protein in cancer. The results presented herein implies for SMAC/Diablo as an important regulator of phospholipids transport and synthesis,

The present study has taken several approaches to elucidate the molecular mechanism underlying the effects of reducing hSMAC levels in lung A549-derived tumors, including immunoblotting, immunohistochemistry, electron microscopy, q-PCR, NGS and functional analysis of the data. SMAC/Diablo-silencing resulted in reduction of Ki-67, a cellular marker of proliferation, both in culture (FIG. 2K) and in tumors (FIG. 4F, G), leading to a quiescent population of cells, as well as to a significant up-regulation of differentiation pathways (FIGS. 10A, B Tables 3-5).

Ki-67 protein is detected during all cell cycle phases, other than resting G₀ phase. During S phase, Ki-67 protein levels markedly increased, with these levels being maintained in interphase and M-phase (Brunu S. et al., 1992. Cell Prolif 25, 31-40). In addition, cells treated with si-hSMAC were arrested in S phase, reflected by inhibition of BrdU incorporation and decreased DNA content in the si-hSMAC-TTs (FIG. 2K, L). The presence of SMAC/Diablo in the nucleus and its function in phospholipids synthesis is in agreement with the observation that during the S phase, the levels of phospholipids inside the nucleus were reduced (Maraldi M. M., et al. 1993. J Cell Sci 107, 853-859).

SMAC/Diablo silencing in tumors resulted in a widely altered expression of genes associated with the extracellular matrix, the cell-secreted collagen and proteoglycan matrix overlying endothelial and epithelial cells, extracellular exosomes, and proteins in the ER and Golgi lumen associated with vesicle formation (FIG. 10A, B, Table 3). These changes may indicate a role for SMAC/Diablo in vesicular trafficking, exosome release, and extracellular matrix (ECM) deposition. Exosome cargo can include proteins, lipids, miRNA, mRNA, and transcription factors with the vesicles serving as extracellular messengers, mediating cell-cell communication, and facilitating cancer progression and metastasis (Fujita, Y., et al., 2016. Cancer Sci 107, 385-390; Minciacchi, V. R., et al., (2015. Semin Cell Dev Biol 40, 41-51). Exosomes released by cancer cells can also transmit signals to stromal and inflammatory cells within the cancer microenvironment, thus impacting the cancer ECM architecture and generating the cancer microenvironment. Indeed, SMAC/Diablo-silencing also affected several factors associated with stromal activity (FIG. 8 , Table 3), Tumor treated with siRNA comprising the nucleic acid sequences set forth in SEQ ID NO:20 and SEQ ID NO:21, targeted to human SMAC/Diablo (si-hSMAC-A-TTs) showed reduced expression of genes associated with inflammation and microenvironment tumorigenicity, including cytokines, chemokines and their related receptors, as well as intracellular proteins associated with inflammatory and immune responses (Table 5). Alterations in the expression of these genes may be associated with reduced tumorigenicity and invasiveness.

As described hereinbelow, SMAC/Diablo silencing is also associated with a modified expression of transporters of metabolites, ions, and enzymes involved in metabolism (FIG. 11A, B, Table 4). The affected enzymes include dehydrogenases and deaminases related to cholesterol, lipid, and nucleotide synthesis, amino acid metabolism, oligosaccharide biosynthesis, and protein glycosylation. Without wishing to be bound by any theory or mechanism of action, the inhibition of cell and tumor growth demonstrated herein for lung cancer cells may result from metabolic dysregulation. In this respect, most of the affected genes were reported to be associated with various cancers. In addition as discussed below, SMAC/Diablo non-apoptotic function is associated with lipid and phospholipids synthesis pathways.

Morphological analysis of A549-derived tumor sections demonstrated structural reorganization of section derived from si-hSMAC-A-treated tumors (si-hSMAC-A-TTs) into glandular, alveolar-like clusters. These structures resembled normal lung alveoli with respect to the arrangement of endothelial cells and macrophages, as visualized by anti-CD-31 (FIG. 7G) and anti-F4/80 (data not shown) antibodies staining, respectively. In contrast, the organization of endothelial cells in control sections (derived from tumors treated with non-targeted siRNA, designated herein si-NT-TTs) typically reflected ongoing tumor angiogenesis. Without wishing to be bound by any theory or mechanism of action, these findings suggest that a reduction in the expression of SMAC/Diablo triggered AT2 differentiation into AT1 cells and to morphological reorganization into lung alveoli-like structures (FIG. 7 ).

A549 cells are non-small cells lung carcinoma cell line, derived from primary tumor. A549 is characterized, as the pre-Alveolar Type II pneumocytes (AT2) of the human lung by expression of high numbers of multilamellar bodies (Foster K. A. et al., 1998. Exp Cell Res, 243, 359-366). While AT1 cells are flattened squamous cells accounting for ˜95% of the alveolar surface and lie adjacent to capillary endothelial cells to form the pulmonary gas exchange region (FIG. 7I), AT2 cells, which cover the remaining 5% of the alveolar surface, have a compact morphology and help clear alveolar fluid via active sodium transport. Unlike terminally differentiated and non-replicating AT1 cells, AT2 cells play multiple roles and have been described as “defenders of the alveolus”. AT2 cells are the main source of cells for renewal of distal lung epithelium and may either regenerate cuboidal surfactant-producing AT2 cells or trans-differentiate into AT1 cells so as to repair damage (Barkauskas, C. E., et al., 2013. J Clin Invest 123, 3025-3036) and maintain normal lung architecture and lung elasticity (Kotton, D. N., and Fine, A. 2008. Cell Tissue Res 331, 145-156; Rock, J. R., and Hogan, B. L. 2011. Annu Rev Cell Dev Biol 27, 493-512; Anversa, P., et al., 2011. Nature Med 17, 1038-1039). The increased expression of several putative AT1 cell markers, including podoplanin (Barkauskas, C. E., et al., 2013, ibid), in si-hSMAC-A-TTs (FIG. 7D) supports the notion that A549 cells undergo differentiation upon reduction of SMAC/Diablo expression.

Further support for the differentiation of cells in the residual “tumor” in si-hSMAC-A-TTs is provided by the NGS data analysis showing up-regulation of genes associated with ion transport (FIG. 11A, Table 4). Increased levels of anoctamin-1 (ANO1), a voltage-sensitive calcium-activated chloride channel that regulates transepithelial anion transport and essential for lung airway physiology (Rock, J. R., et al., 2009. J Biol Chem 284, 14875-14880), of the Ca²⁺-activated potassium channel KCNN4, and of a two-pore potassium (K2P) channel, KSNK1, which are involved in airway surface liquid hydration (Zhao, K. Q., et al., 2012. Am J Physiol Lung Cell Mol Physiol 302, L4-L12), were noted. The same was also found for the epithelial Na⁺ channel (α-ENaC/SCNN1A), a critical factor during the perinatal period of lung development, involved in clearance of lung fluid (Mustafa, S. B., et al., 2014. Exp Lung Res 40, 380-391). Other genes associated with lung maturation, including sodium bicarbonate cotransporters (SLC44A4, NBC), and the sodium- and chloride-dependent glycine transporter 1 (SLC6A9) were down-regulated in si-hSMAC-A-TTs.

Without wishing to be bound by any theory or mechanism of action, these changes in si-hSMAC-TTs may reflect functional changes with respect to airway surface liquid hydration and the clearance associated with the maturation or/and differentiation of A549 to normal-like lung cells.

Cancer progression is associated with stromal activity, characterized by increased deposition of collagen isoforms, laminin and fibronectin, and by heparan sulphate production, as well as of extracellular matrix (ECM) degradative enzymes and metalloproteinases (MMPs). Reduction of SMAC/Diablo levels in tumors also altered stromal formation (FIG. 8 ). As expected for tumors, si-NT-TTs showed a thin network, dispersed throughout the tumor and enriched with vascular formations, with both supporting tumor development (FIGS. 8A and 8B). On the other hand, massive fibrotic structures, resembling scar tissue, were found in si-hSMAC-A-TTs (FIG. 8A).Moreover, the decreased expression of α-SMA and genes associated with TGF-β activity suggests reduced cancer support by the cancer-associated-fibroblasts (CAFs). NGS results demonstrate that metalloproteinase involved in cancer cells invasively, as MMP2 and MMP9 were reduced in si-hSMAC-A-TTs. There seemed to be no effect on collagen formation or vimentin staining in si-NT-TTs or si-hSMAC-A-TTs (data not shown), although α-SMA levels were markedly decreased in si-hSMAC-A-TTs, indicating differences in stromal output. While the myofibroblasts present in si-NT-TTs apparently mediate processes of stromal structures that support tumor progression. The stromal activity in si-hSMAC-A-TTs was more reminiscent of a wound-healing process, such as a scar formation.

Immunofluorescent of staining si-NT-TTs showed the presence of SMAC in the nucleus (FIG. 9A). Nuclear localization of SMAC/Diablo was also detected in the nucleus of 50% of NSCLC patient samples (FIG. 9B, 9C).

Ultrastructure analysis of si-NT-TTs and si-hSMAC-A-TTs using EM clearly demonstrated marked changes in intracellular organelles, including the nucleus (FIG. 10D, 12 ). These changes included decreases in intracellular vesicles of different sizes and densities, such as lysosomes and surfactant-accumulating lamellar bodies, in si-hSMAC-A-TTs (FIG. 10D, 12A). Lamellar bodies are secretory organelles found in AT2 cells that store pulmonary surfactant and are composed of 60-70% PC (Parra, E., and Perez-Gil, J. 2015. Chem Phys Lipids 185, 153-175). As discussed hereinbelow, without wishing to be bound by any specific theory or mechanism of action, the results of the present invention suggest that the observed morphological changes in si-SMAC-TTs are associated with SMAC/Diablo function in phospholipid synthesis.

As demonstrated herein, the expression levels of many genes associated with the formation of vesicle mediating intra- and extra-cellular transport and related to organelles, such as the ER and Golgi and to exosomes, were modified (FIG. 10A, B, 11C, Table 3-4). In addition, the expression levels of genes encoding several enzymes associated with cholesterol and lipid transport, synthesis, degradation and regulation were modified (FIGS. 10C, F, 11A, B). These included StAR-related lipid transfer protein 10 (STARD10), related to lipid transfer, lipase H (LIPH), phospholipase C (PLCB4), acylglycerol-3-phosphate O-acyltransferase (AGPAT2), the elongation of very long chain fatty acids protein 4 (ELOV4) and ELOV3 and ATPase phospholipid transporting 10B (ATP10B; P4-ATPase), a phospholipid flippase that can alter cell shape and which inhibits cell adhesion and spreading, and thus may be associated with the morphological changes induced by SMAC/Diablo silencing. Moreover, analysis of phospholipids and specifically PC content showed a significant decrease (40-50%) in si-hSMAC-A-TTs relative to si-NT-TTs, while phosphatidylethanolamine (PE) levels were increased 2-fold (FIG. 10E). PC is synthesized via two major distinct pathways, namely the triple methylation of PE by phosphatidylethanolamine N-methyltransferase (PEMT) and the de novo or cytidine diphosphate (CDP)-choline (Kennedy) pathway. The enzymes involved in PC biosynthesis are located at the mitochondria associated membranes (MAM) where the transport between ER and mitochondria takes place. A decrease in the expression of key enzymes in the Kennedy pathway, and increased PEMT expression have been demonstrated (FIG. 10G). SMAC/Diablo at the mitochondrial intermembrane space (IMS) may affect phospholipid synthesis via the phosphatidylserine decarboxylase (PSD), an inner mitochondrial membrane enzyme facing the IMS. PSD catalyzes the conversion of phosphatidylserine (PS) to PE with the release of CO₂ (Jacobs R L et al. 2010. J Biol Chem 285, 22403-22413), upon which PE is converted to PC in the ER. In this respect, a connection between mitochondrial lipid metabolism, reflected in the synthesis of mitochondrial phosphatidylethanolamine, the differentiation program of breast cancer cells and loss of tumorigenicity has been recently presented (Keckesova, Z., et al., 2017. Nature 543, 681-686). The present invention now shows (FIG. 18 ) that SMAC interacts with PSD and that upon SMAC deletion, PL and PC levels were decreased 2-fold, while PE levels increased 2-fold (FIG. 10E), suggesting activation of PSD in the absence of SMAC.

The presence of phospholipids in chromatin and the nuclear matrix and the roles of nuclear phospholipids in the structural organization of chromatin and nucleic acid synthesis have been demonstrated (Alessenko, A. V., and Burlakova, E. B. 2002. Bioelectrochemi 58, 13-21). As intra-nuclear phospholipids regulate DNA replication (Maraldi et al. 1993, ibid) changes seen in the expression of many genes upon silencing SMAC/Diablo expression (Tables 3-5) may result from the decrease in phospholipids levels in the cell (FIG. 10 ) and thus, in the nucleus.

Interestingly, SMAC/Diablo has been shown to interact with two nuclear proteins, the aryl hydrocarbon receptor nuclear translocator (ARNT), also known as the oxygen-independent β subunit of hypoxia-inducible factors (HIF-1β) and the Mastermind-like transcriptional co-activator MAML (Wang J et al. 2011. Mol Syst Biol 7, 536). To execute their transcriptional function, HIF factors must form a heterodimer between an oxygen-dependent α subunit (HIF-1α or HIF-2α) and an oxygen-independent subunit (HIF-1β). The HIF-2α-ARNT dimer is involved in cellular adaptation to the oxygen stress related to tumor growth and progression. ARNT is also required for nuclear localization of the transcriptional repressors NPAS1 and NPAS3 (The C H et al., 2006. J Biol Chem 281, 34617-34629). MAML2, as a transcriptional co-activator, plays an important role in Notch signaling, regulating multiple developmental pathways (McElhinny A S et al., 2008. Oncogene 27, 5138-5147). MAML2 binds to proteins such as a cyclic AMP response element-binding protein (CREB or CBP).

Thus, as nuclear SMAC/Diablo binds HIF-1β (ARNT) and MAML2, it may compete with HIF-1α, HIF-2α, NPAS1, or NPAS3 binding to ARNT. Similarly, by binding MAML2, SMAC/Diablo may interfere with interactions of MAML2 with CBP.

Without wishing to be bound by any specific theory or mechanism of action, silencing the expression of SMAC/Diablo by the RNAi molecules of the invention, or interfering with its binding capacity to HIF-1β (ARNT) and/or MAML2 within the nucleus by the peptides of the invention, together with SMAC/Diablo-mediated regulation of phospholipid synthesis and given how nuclear phospholipids control nuclear structure and function, explains the effect of SMAC/Diablo on multiple signaling pathways and on proliferation of cancerous cells.

The following examples are presented in order to more fully illustrate some embodiments of the invention. They should, in no way be construed, however, as limiting the broad scope of the invention. One skilled in the art can readily devise many variations and modifications of the principles disclosed herein without departing from the scope of the invention.

EXAMPLES

Materials and Methods

Materials

The cell transfection agents JetPRIME and JetPEI were from PolyPlus transfection (Illkirch, France), SMAC/Diablo-siRNA were obtained from Genepharma (Suzhou, China). Propidium iodide (PI), sulforhodamine B (SRB), Triton X-100, Tween-20 were obtained from Sigma (St. Louis, Mo.). Paraformaldehyde was purchased from Emsdiasum (Hatfield, Pa.). Dulbecco's modified Eagle's medium (DMEM) was obtained from Gibco (Grand Island, N.Y.). Normal goat serum (NGS) and the supplements fetal calf serum (FCS), L-glutamine and penicillin-streptomycin were obtained from Biological Industries (Beit Haemek, Israel). Horseradish peroxidase (HRP)-conjugated anti-mouse, anti-rabbit and anti-goat antibodies were from KPL (Gaithersburg, Md.). Primary antibodies, their source, and the dilutions used are detailed in Table 1 herein below. A CellTiter-Glo luciferase-based assay and TUNEL stain was obtained from Promega (Madison, Wis.). 3,3-diaminobenzidine (DAB) was obtained from (ImmPact-DAB, Burlingame, Calif.).

TABLE 1 Antibodies used Antibody Source and Cat. No. IHC WB Mouse monoclonal anti- Millipore, Billerica, —  1:10000 actin MA, MAB1501 Mouse polyclonal anti- Abcam, ab8115 1:300 1:2000 SMAC/Diablo Rabbit monoclonal anti- Abcam, ab32150 — 1:2000 pro-caspase 3 Rabbit monoclonal anti- Abcam, ab108333 — 1:1000 caspase 8 Mouse monoclonal anti- Cell Signaling, 9508S — 1:1500 caspase 9 Mouse monoclonal anti- B.D Bioscience, — 1:2000 Cytochrome c 556432 Rabbit polyclonal anti- Abcam, ab32516 — 1:1000 AIF Rabbit polyclonal anti- Abcam, ab137392 1:300 1:2000 XIAP Rabbit monoclonal anti- Thermo Scientific, NY 1:100 — Ki67 RM-9106-s1 Rat monoclonal anti- Santa Cruz 1:150 — F4/80 Biotechnology, Inc. Dallas, TX, sc52664 Rabbit polyclonal anti- Abcam, Cambridge, UK 1:50  — CD31 ab28364 Rabbit polyclonal anti- Abcam, ab5694 1:200 — α-SMA Mouse monoclonal anti- Abcam, ab8978 1:200 — vimentin Mouse monoclonal anti- Abcam, ab10288 1:400 — Podoplanin Rabbit polyclonal anti- Abcam, ab90716 1:250 — Prosurfactant protein C Cell Culture and Transfection

HeLa (human cervical carcinoma) cells, A549 (non-small lung carcinoma) cells, MCF-7 (human breast carcinoma) cells, PC3 (prostate cancer) cells, HepG2 (human hepatocellular carcinoma), MDA-MB-231 (human breast carcinoma), PANC-1 (human pancreatic carcinoma), HTB-72 (SK-MEL-28) (human melanoma), U-87MG (human glioblastoma), U-118MG (human glioblastoma) cells and non-cancerous HaCaT (spontaneously transformed aneuploid immortal keratinocyte cell line from adult human skin), HEK-293 (human embryonic kidney), TREx-293 (human Embryonic kidney), PGA (mouse primary glia and astrocyte) cells were grown in DMEM culture medium and H358 (non-small cell lung cancer), THP1 (human Leukemic monocyte), KG-1α (acute myeloid leukemia) and WI38 (fibroblast derived human lung) cells were grown in RPMI-1640 and EMEM culture medium supplemented with 10% FCS, 2 mM L-glutamine, 100 U/ml penicillin, 100 μg/ml streptomycin, 1 mM sodium pyruvate and non-essential amino acids, and maintained in a humidified atmosphere at 37° C. with 5% CO₂.

RNA Sequences

SMAC/Diablo Human Specific siRNA used include:

si-hSMAC-A: (SEQ ID NO: 20) Sense 5′AAGCGGUGUUUCUCAGAAUUGtt3′ and (SEQ ID NO: 21) antisense 5′AACAAUUCUGAGAAACCCGCtt3′; hSMAC-B: (SEQ ID NO: 22) Sense, 5′GCAGAUCAGGCCUCUAUAAtt3′; (SEQ ID NO: 23) antisense, 5′UUAUAGAGGCCUGAUCUGCtt3′; si-hSMAC-C: (SEQ ID NO: 24) sense 5′CCCGGAAAGCAGAAACCAAtt3′, (SEQ ID NO: 25) antisense, 5′UUGGUUUCUGCUUUCCGGGtt3′; si-hSMAC-D: (SEQ ID NO: 26) sense 5′GCUGGCAGAAGCACAGAUAtt3′, (SEQ ID NO: 27) antisense 5′UAUCUGUGCUUCUGCCAGCtt3′;

si-hSMAC-A1: Sense 5′AAGCGGUGUUUCUCAGAAUUGtt3′, wherein the nucleotides at positions 5, 10, 16 and 21 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:28) and antisense 5′AACAAUUCUGAGAAACCCGCtt3′ wherein the nucleotides at positions 6, 12, and 19 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:29);

si-hSMAC-A2: Sense 5′AAGCGGUGUUUCUCAGAAUUGtt3′, wherein the nucleotides at positions 6, 9, and 21 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:30) and antisense 5′AACAAUUCUGAGAAACCCGCtt3′ wherein the nucleotides at positions 7 and 12 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:31);

si-hSMAC-A3: Sense 5′AAGCGGUGUUUCUCAGAAUUGtt3′, wherein the nucleotides at positions 3, 7, 11, and 16 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:32) and antisense 5′AACAAUUCUGAGAAACCCGCtt3′ wherein the nucleotides at positions 6, 10 and 19 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:33);

si-hSMAC-A4: Sense 5′AAGCGGUGUUUCUCAGAAUUGtt3′, wherein the nucleotides at positions 3, 6, 11, and 21 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:34) and antisense 5′AACAAUUCUGAGAAACCCGCtt3′ wherein the nucleotides at positions 6, and 19 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:35);

hSMAC-B1: Sense, 5′GCAGAUCAGGCCUCUAUAAtt3′, wherein the nucleotides at positions 4, 9, and 15 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:36); antisense, 5′UUAUAGAGGCCUGAUCUGCtt3′, wherein the nucleotides at positions 4, 9, 15, and 18 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:37);

hSMAC-B2: Sense, 5′GCAGAUCAGGCCUCUAUAAtt3′, wherein the nucleotides at positions 4, 9, 13, and 17 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:38); antisense, 5′UUAUAGAGGCCUGAUCUGCtt3′, wherein the nucleotides at positions 6, 12, and 18 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:39);

hSMAC-B3: Sense, 5′GCAGAUCAGGCCUCUAUAAtt3′, wherein the nucleotides at positions 6, 10, and 15 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:40); antisense, 5′UUAUAGAGGCCUGAUCUGCtt3′, wherein the nucleotides at positions 2, 9, and 17 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:41);

hSMAC-B4: Sense, 5′GCAGAUCAGGCCUCUAUAAtt3′, wherein the nucleotides at positions 4, 13, and 17 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:42); antisense, 5′UUAUAGAGGCCUGAUCUGCtt3′, wherein the nucleotides at positions 8, 13, and 18 (marked in bold and underline) are derivatized by 2′-O-Me (SEQ ID NO:43);

non-targeting siRNA (si-NT): sense: 5′ GCAAACAUCCCAGAGGUAU3′ (SEQ ID NO:44) antisense: 5′ AUACCUCUGGGAUGUUUGC3′ (SEQ ID NO:45).

The siRNAs were synthesized by Genepharma (Suzhou, China). Cells were seeded (150,000 cells/well) on 6-well culture dishes to 40-60% confluence and transfected with 10-100 nM si-NT or si-hSMAC/Diablo using the JetPRIME transfection reagent (Illkirch, France), according to the manufacturers' instructions.

Cells were transiently transfected with pcDNA3.1 plasmid (0.5-2 μg DNA) encoding SMAC/Diablo-GFP or pEGFP encoding for GFP using the JetPRIIVIE reagent according to the manufacturer's instructions.

Cell Death Analysis

Cells death was analyzed by propidium iodide (PI) staining and flow cytometer (Beckton-Dickinson, San Jose, Calif.) and BD CellQuest Pro software, or using acridine orange ethidium bromide staining (Abu-Hamad, S., et al., 2009. J Cell Sci, 122(Pt 11): p. 1906-1916).

Determination of Cellular ATP Levels

Cellular ATP levels were estimated using the luciferase-based assay (CellTiter-Glo, Promega). Cells were transfected with si-hSMAC and 48 h and 72 h post-transfection, were washed twice with PBS and seeded in 96-well plates at densities of 5×10⁴ cells/ml (A549, HeLa cells and H358, non-small cell lung cancer cells). ATP levels were assayed according to the manufacturer's protocol and luminescence was recorded using an Infinite M1000 plate reader.

Cell Cycle Analysis

For cell cycle analysis, cells were harvested, washed with PBS and fixed with ice-cold 70% ethanol overnight at −20° C. The cells were then washed with PBS, incubated with RNase A (100 μg/ml) in PBS for 30 min at 37° C. Then the cells were incubated with PI (1 μg/ml) before analysis on a flow cytometer (iCyt Eclipse EC800, UK). Single cells were gated and a minimum of 10,000 cells acquired and analyzed by FACS Eclipse analyzer.

Sulforhodamine B (SRB) Cell Proliferation Assay

Twenty-four hours post-transfection with si-NT or si-hSMAC, cells (10,000/well) were counted and seeded in 96-well plates. After additional 48, 72 or 96 hours, the cells were washed with PBS, fixed with 10% trichloroacetic acid, and stained with SRB. SRB was extracted from the cells using 100 mM Tris base and absorbance at 510 nm was determined using an Infinite M1000 plate reader (Tecan, Mannedorf, Switzerland).

Xenograft Experiments

Five-week-old male athymic Swiss nude mice (weight ˜19-22 g) were obtained from Envigo and allowed a week of acclimatization to their new surroundings. Lung cancer cells A549 (3×10⁶), or breast cancer cells MDA-MB231 (3×10⁶) were injected subcutaneous (s.c.) into the hind leg flanks of the mice. Approval for the experimental protocol was obtained from the Institutional Animal Care and Use Committee of the Soroka University Medical Center. Eleven days after inoculation, the developing tumors were measured in two dimensions with a digital caliper and tumor volume was calculated as follows: volume=X²×Y/2, where X and Y are the short and long tumor dimensions, respectively. Mice with xenografts reaching a volume of 65-100 mm³ were randomized to receive either non-targeting (NT) siRNA or siRNA targeted to human hSMAC (si-hSMAC); 5 animals in each group. Tumors and section thereof that received NT siRNA are designated si-NT-TTs (siRNA non-targeting treated tumors) and tumors and section thereof that received hSMAC siRNA are designated si-hSMAC-TTs (siRNA hSMAC treated tumors). Treatment substances were injected into the established s.c. tumors using the jetPEI delivery reagent (10 μg siRNA/20 μl jetPEI). The tumors were injected (at a volume equal to 10 to 20% of the tumor volume) with si-NT or the appropriate si-hSMAC every three days. Beginning on the day of inoculation, mouse weight and tumor volume were monitored twice a week using a digital caliper. At the end of the experiment, i.e. when tumor volume reached approximately 1300 mm³, the mice were sacrificed using CO₂ gas, the tumors were excised and ex vivo weight was determined. Half of each tumor was fixed in 4% buffered formaldehyde, paraffin-embedded and processed for histological examination, while the second half was frozen in liquid nitrogen and stored in −80° C. for immunoblot analysis.

Quantitative Real-Time PCR (q-PCR)

Total RNA was isolated from cells using an RNeasy mini kit (Qiagen) according to the manufacturer's instructions. Complementary DNA was synthesized from 1 μg total RNA using a Verso cDNA synthesis kit (Thermo Scientific). q-PCR was performed using specific primers (KiCqStart Primers; Sigma Aldrich) in triplicates, using Power SYBER green master mix (Applied Biosystems, Foster City, Calif.). The levels of the target genes were normalized relative to β-actin mRNA levels. Samples were amplified by a 7300 Real Time PCR System (Applied Biosystems) 95° C. for 2 minutes and for 40 cycles using the following PCR parameters: 95° C. for 15 seconds, 60° C. for 1 minute, and 72° C. for 1 minute. The copy numbers for each sample were calculated by the CT-based calibrated standard curve method. The mean fold changes (±SEM) of the three replicates were calculated. The target genes examined and the forward and reverse sequences of the primers used are listed in Table 2 hereinbelow.

TABLE 2 Real-time PCR primers SEQ ID Gene Primers NO. β-Actin Forward   79 5′-ACTCTTCCAGCCTTCCTTCC-3′ Reverse   80 5′-TGTTGGCGTACAGGTCTTTG-3′ SMAC/ Forward   81 Diablo 5′-CTGACTTCTACTTCCAGGCTGTT-3′ Reverse   82 5′-GCTCCTATGATCACCTGCCA-3′ XIAP Forward   83 5′-GCACGGATCTTTACTTTTGGG-3′ Reverse   84 5′-GGGTCTTCACTGGGCTTC-3′ cIAP1 Forward   85 5′-ATCTAGTGTTCCAGTTCAGCC-3′ Reverse   86 5′-ACCACTTGGCATGTTCTACC-3′ cIAP2 Forward   87 5′-CATGCCAAGTGGTTTCCAAG-3′ Reverse   88 5′-TCTGCATTTTCATCTCCTGGG-3′ AIF Forward   89 5′-AAGCACGCTCTAACATCTGG-3′ Reverse   90 5′-TTCTCCAGCCAATCTTCCAC-3′ Cyto- Forward   91 chrome c 5′-TTTGGATCCAATGGGTGATGTTGAG-3 Reverse   92 5′TTGAATTCCTCATTAGTAGCTTTTTTGAG-3 caspase  Forward   93 8 5′-GGAGCTGCTCTTCCGAATTA-3 Reverse   94 5′-GCAGGTTCATGTCATCATCC-3′ caspase  Forward   95 9 5′-CTAGTTTGCCCACACCCAGT-3′ Reverse   96 5′-TGCTCAAAGATGTCGTCCAG-3′ caspase  Forward   97 3 5′-AGGACTCTAGACGGCATCCA-3′ Reverse   98 5′-TGACAGCCAGTGAGACTTGG-3′ Ki-67 Forward   99 5′-CTTTGGGTGCGACTTGACG-3′ Reverse  100 5′-GTCGACCCCGCTCCTTTT-3′ IL-6 Forward  101 5′-CTCAATATTAGAGTCTCAACCCCCA-3′ Reverse  102 5′-AAGGCGCTTGTGGAGAAGG-3′ STAT3 Forward  103 5′-GCTTTTGTCAGCGATGGAGT-3′ Reverse  104 5′-TCTGCTAATGACGTTATCCAGTT-3′ NOS1 Forward  105 5′-CAGTGATGATAGGATAAAGGAGGGA-3′ Reverse  106 5′-CATCATGAGCCCGTCCGC-3′ SOD2 Forward  107 5′-TAAACGTAGTGTCCACGGCA-3′ Reverse  108 5′-TTTCCACACGCTTATCTGCGA-3′ FOXRED2 Forward  109 5′-TCAACCTCCCAAGTAGCTGG-3′ Reverse  110 5′-TTAGGAGGCCAAGACAGGTG-3′ PTGS2 Forward  111 5′-CTCCTGTGCCTGATGATTGC-3′ Reverse  112 5′-AACTGATGCGTGAAGTGCTG-3′ PCSK5 Forward  113 5′-TGGCACAGTCTACCGGAAAT-3′ Reverse  114 5′-CCTGAGAGTGGAATGGTGGT-3′ SLC4A4 Forward  115 5′-GGCTTCTTCTCTCCCACAGT-3′ Reverse  116 5′-TTCTTGGTTTGATGCCGGTG-3′ GAS6 Forward  117 5′-GGAGAAGACACCACCATCCA-3′ Reverse  118 5′-TCCCAGGTTGATTCAGTCCC-3′ Next-Generation Sequencing (NGS) and Functional Analysis

Libraries were prepared by the INCPM-RNA-seq unit (Weizmann Institute, Israel). Briefly, polyA fraction (mRNA) was purified from 500 ng of total RNA, isolated as above, followed by fragmentation and generation of double stranded cDNA. End repair, a base addition, adapter ligation and PCR amplification steps were performed according to established methods. Libraries were evaluated by Qubit and TapeStation. Sequencing libraries were constructed with barcodes to allow multiplexing of 20 samples in one lane. Between 22 and 26 million reads single-end 60-bp reads were sequenced per sample on Illumina HiSeq 2500 V4 instrument.

Bioinformatics analyses were carried out at the Bioinformatics Core Facility at the National Institute for Biotechnology in the Negev, Ben-Gurion University. Raw sequence reads were assessed for quality using FASTQC and further trimmed for removal of remaining adaptors and low quality bases using Trimmomatic. The trimmed reads from each sample were separately aligned to the human and mouse genomes (GRCh38 and GRCm38.75, respectively) using STAR v2.3.0 with default settings. An average of 23.7±0.8 million reads per sample was obtained. Of these, an average of 13, 2.6, 7.8 and 0.3 million reads were mapped to human only, mouse only, both human and mouse, and none of them, respectively. After rejection of multi-mapped reads, a total of 11.5±2.5 human-specific, uniquely mapped reads, and 2.3±1.7 mouse-specific, uniquely mapped reads were subjected for further analysis. The number of aligned reads per gene per sample were counted using HTSeq count with “intersection-nonempty” (to handle reads that overlap with more than one gene) and “no stranded” as parameters. The other parameters were set to their default. Normalization and statistical analysis for differential expression were carried out using DESeq2 v1.6.3. Fold change values were converted to linear scale, with a minus sign indicating down-regulation.

Differentially expressed genes were defined as those having a p-value <0.05, and linear fold change >1.5 and <−1.5. Functional analysis was performed using the Gene Ontology system, DAVID and Expander software tools.

Patient-Derived Samples

Chronic lymphocytic leukemia (CLL) blood samples were obtained from Soroka University Medical Center from patients not receiving any disease treatment. Blood samples were also obtained from healthy volunteers. Peripheral blood mononuclear cells (PBMCs) were isolated from venous blood of CLL patients by Ficoll-Paque PLUS (GE Healthcare) density gradient centrifugation as described previously (Admoni-Elisha, L., et al., 2016. PLoS One, 2016. 11(4): p. e0148500).

Fresh lung cancerous and non-cancerous tissue specimens were obtained from the same lung cancer patients undergoing either pneumonectomy or pulmonary lobectomy to remove tumor tissue and were immediately frozen in liquid nitrogen and maintained at −80° C. until use. Cancer and normal lung tissue surrounding the tumor were validated by hospital pathologists. Proteins were extracted from the tissue sample using a lysis buffer (50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 1 mM EDTA, 1.5 mM MgCl₂, 10% glycerol, 1% Triton X-100, a protease inhibitor cocktail (Calbiochem), followed by sonication and centrifugation (10 min, 600 g). Protein concentration was determined and samples were stored in −80° C. until use.

The research was approved by the Soroka University Medical Center Advisory Committee on Ethics in Human Experimentation and conducted in accordance with national laws and regulations, the ethical principles set forth in the Declaration of Helsinki and with good clinical practice as described in the ICH guidelines. Written informed consent was obtained from all participants prior to entry into the study. All subjects received a copy of their signed and dated informed consent form.

Immunohistochemistry

Tissue microarrays (MC5003, LC807) containing cancer and normal tissues purchased from US Biomax (US Biomax, Inc. USA) and formalin-fixed and paraffin-embedded tumor sections were immunohistochemistry (IHC) stained. Sections were deparaffinized using xylene and a graded ethanol series. Endogenous peroxidase activity was blocked by incubating the sections in 3% H₂O₂ for 10 minutes. Antigen retrieval was performed in 0.01M citrate buffer (pH 6.0) in 95° C.-98° C. for 20 minutes. After washing sections with PBS containing 0.1% Triton-X100 (pH 7.4), non-specific antibody binding was reduced by incubating the sections in 10% normal goat serum for 2 hr. After decanting excess serum, sections were incubated overnight at 4° C. with primary antibodies (sources and dilutions are detailed in Supplementary Table 1). Sections were washed with PBST. For IHC, endogenous peroxidase activity was blocked by incubating the sections in 3% H₂O₂ for 15 min. After washing thoroughly with PBST, the sections were incubated for 2 h with anti-mouse or anti rabbit (1:250) secondary antibodies conjugated to HRP, as appropriate. Sections were washed five times in PBST and the peroxidase reaction was subsequently visualized by incubating with 3,3-diaminobenzidine (DAB) (ImmPact-DAB, Burlingame, Calif.). After rinsing in water, the sections were counterstained with hematoxylin, and mounted with Vectashield mounting medium (Vector Laboratories, Burigame, Calif.). Finally, the sections were observed under a microscope (Leica DM2500) and images were collected at 20× magnification with the same light intensity and exposure time.

Immunoblot Staining

For immunostaining, membranes containing electro-transferred proteins following SDS-PAGE were blocked with 5% non-fat dry milk in TBS (10 mM Tris 150 mM NaCl, pH 7.8) containing 0.1% Tween-20, incubated with the primary antibodies (sources and dilutions as detailed in Table 1 or in the corresponding example). Following washing 3 times with TBST (10 mM Tris 150 mM NaCl, pH 7.8 containing 0.05% Tween-20) the membranes were incubated with HRP-conjugated anti-mouse or anti-rabbit (1:10,000) or anti-goat (1:20,000) IgG. Enhanced EZ-ECL chemiluminescence detection kit (Cat: 20-500-120), Biological Industries, Beit—Haemek, Ill.) was used for detection of HRP activity. Band intensity was quantified using FUSION-FX (Vilber Lourmat, France).

TUNEL Assay

Tumor sections were processed for the TUNEL assay using the DeadEnd Fluorometric TUNEL system (Promega, Madison, Wis.) according to the manufacturer's instructions. Sections were deparaffinized, equilibrated in PBS, permeabilized with proteinase K (20 μg/ml in PBS), post-fixed in 4% paraformaldehyde, and incubated in TdT reaction mix (Promega) for 1 h at 37° C. in the dark. Slides were then washed in 2× saline-sodium citrate (SSC) buffer and counter-stained with PI (1 μg/ml), and cover slipped with Vectashield mounting medium (Vector Laboratories, Burigame, Calif.). Fluorescent images of apoptotic cells (green) and cell nuclei (red) were captured using a confocal microscope (Olympus 1X81).

Lipid Extraction

Lipids were extracted from si-NT-TTs and si-hSMAC-A-TTs as described previously (Folch, J., M. et al., 1957. J Biol Chem, 226(1): p. 497-509.). Briefly, 10-20 mg of tissue were added to CHCl₃/MeOH (2:1, v/v) (7.5 mg/ml) and homogenized twice using ultrasound sonication. Water (12 μl/mg) was added to the suspension; the tube was closed with a glass cap and shaken at room temperature for 2 h at 400 rpm. The suspension was heated to 60° C. for 10 min and subsequently stored at 8° C. for more than 1 h in order to denature proteolipids. Undissolved material was separated by filtration through a Syringe Filter (0.4 μm pore). After evaporation of solvent, the residue was re-dissolved in CHCl₃/MeOH. The suspension was filtered and the solvent was evaporated again. The weight of the extracted lipids was determined.

Estimation of Phospholipids, Phosphatidylcholine and Phosphatidylethanolamine

Phospholipids content of the lipids extracted from si-NT-TTs and si-hSMAC-A-TTs as described above was determined based on the formation of a complex of the phospholipids with ammonium ferrothiocyanate as described previously (Stewart, J. C., 1980. Anal Biochem, 104(1): p. 10-14). The absorbance at 488 nm was determined and the amounts of phospholipids were calculated using phosphatidylcholine (PC) a standard (10-100 μg). For phosphatidylcholine (PC) determination, samples of the extracted lipids were analyzed using ammonium thiocyanatocobaltate reagent as described previously (Yoshida, Y., E. et al., 1979. J Biochem, 86(3): p. 825-828). The absorbance at 316 nm was measured and PC amount was calculated using a phosphatidylcholine standard (10-100 μg).

Phosphatidylethanolamine (PE) content of the lipids extracted from si-NT-TTs and si-hSMAC-A-TTs was measured using a fluorescence-based assay as described previously (Jae-Yeon Choi et al. 2018. J. Biol. Chem 293, 1493-1503). Briefly, samples of lipid extracted from tumors as described above were dissolved in chloroform and after then chloroform was evaporated under gas nitrogen. The dried extract was then re-suspended in 0.8 mM Triton X-100. To 20 μl of lipid samples, reaction mixture including 50 μl reaction buffer (80 mM NaCl, 2 mM KPO4, pH 7.4), 30 μL H₂O and 12.5 μl borate buffer (100 mM boric acid, NaCl 75 mM, sodium tetraborate 25 mM, pH, 9) were added and placed in 96 well plate and mixed well. 12.5 μl of 100 μM distyrylbenzene-bis-aldehyde (DSB-3), kindly provided by Prof. Uwe Bunz, (Organisch-Chemisches Institute, Heidelberg, Germany) prepared in 10 mM KH₂PO₄, pH 7.4 were then added. After 2 h of incubation in dark with shaking at 100 rpm, fluorometric detection of PE was carried out at λex=403 nm, λem=508 nm, using a plate reader. A standard curve using purified PE was carried out in parallel.

Example 1: Expression of SMAC/Diablo in Tumors

Expression levels of SMAC/Diablo in tissue microarray slides containing samples of randomly selected normal (10-20 healthy) controls and different types of malignant cancer (40 to 80) were assessed by immunohistochemistry (IHC) using SMAC/Diablo-specific antibodies (FIG. 1A). Marked increase in SMAC/Diablo expression level was observed in various cancer tissues, including lung, B-lymphoma, testis, colon, stomach, breast, prostate, and skin. No significant increase in SMAC/Diablo level was observed in brain, ovary, uterine, bladder, cervix, uterus, esophagus, head and neck, intestinal mucous membrane, kidney, liver, or oral cavity cancer tissues (data not shown).

Levels of SMAC/Diablo expression were higher in samples of lung cancer (non-small cell lung cancer; NSCLC), relative to samples of adjacent healthy tissue from the same lung (FIG. 1B). Quantitative analysis showed 3.5-fold higher levels of SMAC/Diablo expression in NSCLC tissue samples, relative to corresponding healthy tissue (FIG. 1D). Immunoblotting analysis showed an approximately six-fold increase in the expression of SMAC/Diablo in peripheral blood mononuclear cells (PBMCs) from chronic lymphocytic leukemia (CLL) patients, as compared to PBMCs from healthy donors (FIG. 1C, D).

The expression level of SMAC/Diablo in cancerous cell lines, including HeLa, A549, H358, HepG2, MCF7, MDA-MB-231, U-87MG, U-118MG, THP1, and KG-1α cells, were about 2-4 fold higher compared to the non-cancerous TREx-293, HEK-293, HaCaT and WI-38 cell lines (FIG. 1E,F).

Example 2: Silencing of SMAC/Diablo Inhibits Cell Growth

The function of SMAC/Diablo in cancer was explored by silencing its expression in a number of human-derived cancer cell lines of various origins (i.e., HeLa, A549, H358, MCF-7, PC3, HepG2, MDA-MB-231, PANC-1, and HTB-72) using siRNA specific to human SMAC/Diablo (designated si-hSMAC-A, comprising a sense stand having the nucleic acid sequence set forth in SEQ ID NO: SEQ ID NO:20 and an antisense strand having the nuclkeic acid sequence set forth in SEQ ID NO:21). SMAC/Diablo protein expression levels were markedly decreased (80-90%) in all tested cell lines (FIG. 2A), with a maximum of 90% decrease seen after 48 h. Ninety-six h post-transfection, the inhibition level dropped to 65%, most probably due to degradation of the siRNA or its dilution in the growing cells (exemplified with non-small lung carcinoma cell lines A549 and H358 FIG. 2B, C and Hela Cells, FIG. 2D, E).

The effect of the SMAC/Diablo silencing on cell growth was examined using the sulforhodamine B (SRB) assay. In the three cell lines tested (HeLa, A549, and H358), a marked 70-80% decrease in cell proliferation was observed 120 h post-transfection with si-hSMAC-A, whereas the control transfected with non-targeting siRNA (si-NT) showed no significant effect on cell growth (FIG. 2F). Interestingly, in immortalized non-cancerous cell lines, including WI38 and HaCat, si-hSMAC-A decreased SMAC/Diablo expression (FIG. 2G), yet did not affect cell growth (FIG. 2H). Three other siRNAs designed to target hSMAC (B to D as described hereinabove) were also found to inhibit SMAC/Diablo expression and cell growth to various degrees (FIG. 2I, 2J).

si-hSMAC-A and si-hSMAC-B were modified by 2′-O methylation (2′-O Me) to form si-hSMAC-A1, si-hSMAC-A2 si-hSMAC-A3 si-hSMAC-A4 si-hSMAC-B1 si-hSMAC-B2 si-hSMAC-B3 and si-hSMAC-B4 described hereinabove. The effect of these modified forms on SMAC/Diablo expression and on cell proliferation was examined using 30 and 50 nM of each inhibitory RNA molecule in the lung cancer line A549. Of the examined si-hSMAC-A modified molecules, si-hSMAC-A1 and si-hSMAC-A4 were found to be most active in reducing cell proliferation (FIG. 14C), and of the examined si-hSMAC-B modified molecules, si-hSMAC-B2 and si-hSMAC-B3 were found to be most active (FIG. 14F).

Lung cancer cells (A549) treated with si-hSMAC-A, the most active siRNA, showed a significant decrease in the number of cells expressing the cell proliferation factor/marker Ki-67 as reflected by a decrease of about 85% in Ki-67 positive cells (FIG. 2K).

As Ki-67 levels are increased with cell cycle progression, this decrease in expression suggests that cells treated with si-hSMAC-A do not advance in the cell cycle. Cell cycle analysis revealed an about 3-fold increase in the number of cells in S-phase in si-hSMAC-treated A549 cells relative to etoposide-treated cells (a chemotherapy medication used for the treatments of a number of types of cancer, including lung cancer) (FIG. 2L), suggesting that SMAC/Diablo-depleted cells have decreased capacity to proceed in S phase.

Silencing SMAC/Diablo in HeLa, A549, and H358 cells reduced cellular ATP levels by 20-35% (FIG. 2M), which may contribute to the observed inhibition of cell growth.

There was no significant cell death (5-10%) of HeLa, A549 or H358 cells silenced for SMAC/Diablo (FIG. 3A-C), suggesting that the decrease in cell growth was due to inhibition of cell proliferation rather than enhanced cell death. As expected, cell death was induced by selenite. Moreover, apoptosis was induced by over-expressing SMAC/Diablo or SMAC/Diablo-GFP in HeLa, A549 and H358 cells in a concentration- and time-dependent manner, again as expected (FIG. 3D-F).

Example 3: Silencing SMAC/Diablo Expression Inhibits Tumor Growth in Mice

The effect of si-hSMAC-A was tested on a sub-cutaneous (s.c) tumor xenograft of A549 cells established in nude mice (FIG. 4 ). Following tumor formation (75-90 mm³), the mice were divided into three matched groups, and injected every 3 days with either si-NT (group 1) or si-hSMAC-A at 350 nM (group 2) or 700 nM (group 3). Tumor growth was followed for 39 days (FIG. 4A). In animals injected with si-NT-treated tumors (TTs), tumor volume increased by 13-fold, whereas 700 nM si-hSMAC-A treatment reduced growth markedly (FIG. 4A). Comparing tumor sizes at the end point revealed decrease of 50% and 85% in si-hSMAC-A-TTs at the 350 nM and 700 nM levels, respectively.

All mice were sacrificed 39 days post-cell inoculation, and the tumors were excised (FIG. 4B) and weighed (FIG. 4C). This revealed 40% and 75% decreases in tumor weight for 350 and 700 nM si-hSMAC-A-TTs, respectively, values similar to the calculated tumor volumes (FIG. 4A). Half of each tumor was next excised, fixed, and paraffin sections were analyzed by IHC. si-NT-TTs were strongly immunostained with anti-SMAC/Diablo antibodies. However, as expected, the staining was very weak in si-hSMAC-A-TTs (FIG. 4D). Similar results were obtained using qPCR (FIG. 4E). No expression of the alternative splice variant SMAC/Diablo-ε was found in the A549-derived tumors (FIG. 4E), although this isoform was previously detected in healthy human tissues and in several cancer cell lines (Martinez-Ruiz, G. U., et al., 2014. Int J Clin Exp Pathol 7, 5515-5526).

The expression levels of the cell proliferation factor Ki-67, as analyzed by IHC staining or q-PCR, were markedly decreased (˜80%) in the si-hSMAC-A-TTs (FIG. 4F, G), similar to the results obtained with cancer cells in culture (FIG. 2K). Similar results were also obtained with MDA-MB-231 cells (FIG. 5 ).

Example 4: Silencing of SMAC/Diablo Alters the Expression of Apoptosis-Associated Proteins

TUNEL staining revealed a lack of significant apoptosis in either si-NT-TTs or si-hSMAC-A-TTs from A549-derived xenograft tumors (data not shown). As SMAC/Diablo released from mitochondria during apoptosis binds to and counters the activities of IAPB leading to the release of bound caspases (Verhagen, A. M., et al. 2000. Cell 102, 43-53), the expression levels of XIAP1, cIAP1, and cIAP2, as well as of pro-apoptotic proteins including caspases 3, 8, and 9, Cyto c, and AIF were analyzed. The expression levels of these genes (mRNA) were noticeably decreased, as revealed by q-PCR (FIG. 6A, B). A reduction of protein expression level was demonstrated by IHC for XIAP (data not shown).

In cell culture, immunoblotting (FIG. 6C, D) and q-PCR (FIG. 6E) of HeLa, A549, and H358 cells treated with si-hSMAC-A showed decrease in the expression level not only of SMAC/Diablo but also of its binding protein, XIAP. SMAC/Diablo silencing also affected expression levels of apoptosis-related proteins, including caspases 3, 8, 9, albeit in a transient effect, with maximum inhibition being noted at 48 h, followed by a lessening of the effect 96 h after transfection.

These results suggest cross-talk between the levels of expression of SMAC/Diablo and those of a variety of apoptosis-related proteins.

Example 5: Silencing SMAC/Diablo Expression Alters Residual Tumor Morphology

Hematoxylin and eosin (H&E) staining of sections from si-NT-TTs and si-hSMAC-A-TTs lung cancer xenografts demonstrated a mostly similar morphology of lung cancer tissue with cyst-like structures (FIG. 7A). However, further morphological analysis revealed that in si-hSMAC-A-TTs, the cells were organized in glandular-like clusters, surrounded by a chain of cells (FIG. 7B), which were not seen in si-NT-TTs (FIG. 4B). These features can be interpreted as indicative of the cancer cells in si-hSMAC-A-TTs having undergone a differentiation process. To investigate this point, we analyzed the expression of the pulmonary-associated surfactant protein c (SP-C) (FIG. 4C), a component of the surface-active lipoprotein complex that is required for proper biophysical function of the lung, and found in alveolar epithelial type II (AT2) cells (Barkauskas, C. E. et al., 2013. J Clin Invest 123, 3025-3036). No significant differences in the staining of SP-C in si-NT-TTs and si-SMAC-A-TTs were found (FIG. 4C). The expression of the AT1 cells marker podoplanin (also known as T1α, PDPN), a membranal mucin-type sialoglycoprotein (Barkauskas et al., ibid), was also assessed (FIG. 4D, E). The higher expression levels of podoplanin in si-hSMAC-A-TTs support the suggestion that cells in the residual tumor had undergone differentiation into AT1-like cells. (FIG. 4F) Photomicrograph of si-hSMAC-A-treated tumor stained with toluidine blue. Arrows indicate glandular-like clusters surrounded by a chain of cells.

Further structural analysis revealed that the cells organized in a chain around the glandular-like structures were positively stained for the endothelial cell marker CD31 (FIG. 7G), and were organized in a manner resembling lung alveoli. In contrast, in si-NT-TTs, the CD31-positive cells were flattened and randomly dispersed over the entire area of the tumor tissue (FIG. 7G). The results of the histological analysis could reflect a scenario whereby si-NT-TTs CD31-positive cells are involved in the process of tumor angiogenesis, while in si-hSMAC-A-TTs, the cellular organization more closely resembles the normal physiological alveolar endothelial arrangement designed for O₂ exchange. A schematic presentation of a cross-section through alveoli is offered for comparison with the glandular/alveolar-like structures observed in the si-hSMAC-A-TTs (compare FIGS. 7H and I).

Further support for this view comes from analysis of the formation of stroma in H&E-stained si-NT-TTs and si-hSMAC-A-TTs (FIG. 8 ). While the stromal structures in si-NT-TTs were thin, appeared fragile, and were dispersed throughout the tissue, in si-hSMAC-TTs, massive fibrotic structures, resembling scar tissue, could be seen (FIG. 8A). In addition, the stromal structures in si-NT-TTs were enriched with vascular formations, associated with angiogenesis; these were barely noticeable in si-hSMAC-A-TTs (FIG. 8B).

Staining with Sirius red and of vimentin, staining collagen and intermediate filaments, respectively, appeared to be similar in si-NT-TTs and si-hSMAC-A-TTs (data not shown). In contrast, staining for α-SMA, a myofibroblast marker, was observed mainly in si-NT-TTs, and was significantly reduced in si-hSMAC-A-TTs (FIG. 8C), suggesting reduced myofibroblast infiltration.

Example 6: Over-Expressed SMAC/Diablo is Found in the Nucleus and Cytosol

Interestingly, it was noticed that although SMAC/Diablo is known as a mitochondrial protein, high levels were also detected in the nucleus and cytosol of NSCLC tissue microarray samples (FIG. 9 ). IHC analysis revealed that SMAC/Diablo was found in the nucleus in ˜50% of the samples (data not shown). The sub-cellular localization of SMAC/Diablo in si-NT-TTs was further analyzed by immunofluorescence staining using anti-Cyto c antibodies as mitochondria markers and confocal microscopy (data not shown). It was found SMAC/Diablo and Cyto c were co-localized in si-NT-TTs. Here too, SMAC/Diablo was found in addition to mitochondria also in the nuclei. As expected, no SMAC/Diablo was detected in si-SMAC-A-TTs.

Nuclear localization of SMAC/Diablo was also detected in lung cancer tissue by IHC analysis (FIG. 9B). Analysis of various types of cancer (FIG. 1 ) detected nuclear localization of SMAC/Diablo, in addition to NSCLC, only in B diffuse lymphoma (FIG. data not shown). Cytosol-localized SMAC/Diablo was also found in patient-derived NSCLC tumors over-expressing SMAC (FIG. 9C).

Example 7: Next-Generation Sequencing (NGS) of si-NT-TTs and si-hSMAC-TTs and Functional Analysis

NGS was used to investigate changes in patterns of gene expression in si-NT-TTs and si-hSMAC-A-TTs (FIG. 10 , and Tables 3-5). Such analysis revealed 848 genes, half of which are of human origin (428; 50.5%) and half of which are of murine origin (420; 49.5%), that displayed significant changes (≥1.5-fold change, adjusted P value<0.05). As si-hSMAC is human-specific, any effect on mouse gene expression must be mediated by the human tumor cells.

Of the human genes the expression of which was modified following SMAC/Diablo silencing, about 186 were up-regulated and 242 were down-regulated. Functional analysis (Gene Ontology system, DAVID) of gene expression in si-NT-TTs and si-hSMAC-A-TTs revealed differential expression of genes associated with key functions and pathways related to tumorigenicity (FIG. 10 , Tables 3-5). The major functional groups were changes were seen are presented below.

Genes associated with membranes, organelles and extracellular matrix—The expression of about 200 genes associated with cell membrane, exosomes, and extracellular matrix and proteins found in the lumen of the ER and Golgi were altered. While genes associated with cell membrane, extracellular exosomes and extracellular matrix were found to be both up- and down-regulated, genes associated with ER lumen and Golgi were only down-regulated (FIG. 10A, B, Table 3). Some of these results were validated by q-PCR (FIG. 11 ).

Genes associated with lipid transport, synthesis and regulation—Alterations in the membranal system could reflect that membrane components, such those involved in phospholipid synthesis, were impaired upon SMAC reduction. Indeed, si-SMAC-TTs showed alterations in the expression levels of genes associated with the transport, synthesis and regulation of lipids (FIG. 10C, Table 4). These included the elongation of long chain fatty acids protein 4 (ELOV4, 145-fold) and ELOV3 (7-fold); ATP10B (25-fold) that mediates the transport of phospholipids from the outer to the inner leaflet of various membranes; StARD10, involved in the transfer of phosphatidylcholine (PC) and phosphatidyetanolamline (PE) between membranes; LIPH lipase, catalyzing the production of 2-acyl lysophosphatidic acid, and phospholipase C, cleaving phospholipids, that were all up-regulated. At the same time, glycerol kinase (GK), diacylglycerol kinase delta (DGKD), that phosphorylates diacylglycerol to produce phosphatidic acid, and acyl-CoA dehydrogenase (ACAD10), that participate in the beta-oxidation of fatty acids in mitochondria, were all decreased in si-SMAC-A-TTs (FIG. 10C, Table 4). In addition, the expression of SLC44A4 that mediate choline transport was increased in si-SMAC-A-TTs (FIG. 11A).

Transporters of metabolites and ions and cell metabolism—Another interesting group of differentially expressed genes includes those related to the transport of metabolites and ions (FIG. 11A, B, Table 4). In si-hSMAC-TTs, down-regulated genes included several members of the solute carrier family (SLC), which mediate sodium/bicarbonate, sodium/potassium/calcium co-transport, the organic anion transporter, which transports the prostaglandins PGD2, PGE1, PGE2, and the mitochondrial iron transporter. Other genes down-regulated in si-hSMAC-A-TTs are associated with lung maturation, including sodium bicarbonate co-transporters (SLC4A4, NBC), and the sodium- and chloride-dependent glycine transporter 1 (SLC6A9).

Up-regulated genes included the Ft/sucrose symporter, genes involved in the regulation of lipid metabolism, the thiamine pyrophosphate (TPP) transporter, a cation/proton antiporter, and those encoding several channels for K⁺, Na⁺, Cl⁻ (FIG. 14A, Table 4). Increased levels of anoctamin-1 (ANO1), a voltage-sensitive calcium-activated chloride channel that regulates trans-epithelial anion transport that is essential for lung airway physiology (Rock, J. R., et al. 2009. J Biol Chem 284, 14875-14880) and of the Ca²⁺-activated potassium channel KCNN4 and a two-pore potassium (K2P) channel, KSNK1, which are involved in airway surface liquid hydration (Zhao, K. Q et al. 2012. Am J Physiol Lung Cell Mol Physiol 302, L4-L12), were noted. The same is true for the epithelial Na⁺ channel (α-ENaC/SCNN1A), a critical factor during the perinatal period of lung development, involved in clearance of lung fluid ((Mustafa, S. B., et al. 2014. Exp Lung Res 40, 380-391).

Metabolism-related genes whose expression was altered in si-hSMAC-A-TTs included dehydrogenases and deaminases responsible for mediating the conversion of oxaloacetate to phosphoenolpyruvate, alcohol dehydrogenase, hexose-6-phosphate dehydrogenase, and adenosine deaminase, all of which were down-regulated (FIG. 11B, Table 4). Up-regulated genes encoded for enzymes involved in nucleotide synthesis (cytidine deaminase, ectonucleoside triphosphate diphosphohydrolase, calcium-activated nucleotidase 1), amino acid metabolism (peptidyl arginine deiminase, glutamic pyruvate transaminase), oligosaccharide biosynthesis, and protein glycosylation (glycosyltransferases, fucosyltransferases, beta-galactoside alpha-2,3-sialyltransferase, polypeptide N-acetylgalactosaminyltransferase) (FIG. 11B, Table 4). Most of the transporters and metabolism-related proteins with modified expression in the si-hSMAC-A-TTs have already been reported to be associated with several cancers, in addition to the lung cancer analyzed here (Table 4).

Inflammation and the tumor microenvironment—The si-hSMAC-A-TTs also showed a reduction in the expression of genes associated with inflammation and the tumor microenvironment, including cytokines, chemokines, their related receptors, and intracellular proteins associated with inflammatory and immune responses (Table 5). Selected results were confirmed by q-PCR (FIG. 11C). These results included IL-6, known to be involved in tumorgenicity and the activation of transcription factors, such as STAT3, associated with oncogenicity. In addition, the results of NGS and q-PCR analysis showed a reduction in the levels of nitric oxide synthase 1 (NOS1), an essential factor for tumorgenicity and angiogenesis, and of mitochondrial superoxide dismutase 2 (SOD2) (Table 4, FIG. 11C) as well as genes associated with the expression of transforming growth factor β (TGF-β) and metalloproteinases (MMP2 and MMP9) in si-hSMAC-A-TTs (Table 5). Similar staining of si-NT-TTs and si-hSMAC-A-TTs with the macrophage-specific antibody F4/80 was seen (data not shown).

A conclusion following from these results is that up-regulation of the expression of SMAC/Diablo in tumor cells may be associated with an increase in the inflammatory activity that is essential for tumorigenicity, invasiveness, metastasis, and angiogenesis.

TABLE 3 List of selected genes associated with exosome and vesicle formation differentially expressed between si-NT- and si-hSMAC-A-treated A549 cells-derived tumors, based on NGS analysis Fold change Gene (Uniport accession) (p value) Proposed function Relation to cancer EXOSOMES CD9- (TSPAN29)  1.5 Glycoprotein/integrin belongs a prognostic biomarker in [HGNC: 1709] (1.1 × 10⁻⁴) to tetraspanin family NSCLC CD63- (TSPAN30)  3.5 Glycoprotein/integrin belongs a prognostic biomarker in transmembrane channel- (3.88 × 10⁻¹²)  to tetraspanin family. Involved NSCLC like 4 [HGNC: 22998] intracellular vesicular transport processes TSPANS-tetraspanin 8  1.6 Glycoprotein/integrin belongs A metastasis-promoting [HGNC: 11855] (2.3 × 10⁻⁵) to tetraspanin family tetraspanin TSPAN13-  1.8 GLYCOPROTEIN/INTEGRIN Overexpressed in prostate tetraspanin 13 (5.1 × 10⁻⁴) BELONGS TO cancer [HGNC: 21643] TETRASPANIN FAMILY VAMPS- vesicle-associated  1.9 V-SNARE PROTEIN, Reduces cancer invasive membrane protein 8 (1.0 × 10⁻⁵) INVOLVED IN DOCKING activity [HGNC: 12647] AND/OR FUSION OF SYNAPTIC VESICLES RAB17- member RAS  1.9 A SMALL GTPASE Reduces cancer invasive oncogene family (1.0 × 10⁻⁴) Associated with epithelial activity [HGNC: 16523] polarity EPCAM- epithelial cell  2.7 Epithelial cell-cell adhesion, Poor prognosis and adhesion molecule  (3.1 × 10⁻¹¹) proliferation, migration, metastasis [HGNC: 11529] signaling and differentiation CEACAM5 (CD66e)-  2.2 Associated with adhesion and Involved in cancer carcinoembryonic antigen- (3.2 × 10⁻⁵) invasion metastasis related cell adhesion molecule 5 [HGNC: 1817] CANT1- calcium activated  1.5 A nucleotidase with a Overexpressed in prostate nucleotidase 1 (4.4 × 10⁻⁴) preference for UDP cancer [HGNC: 19721] HSPG2 (Perlecan)- −1.7 A component of the vascular Associated with lung heparan sulfate (3.5 × 10⁻⁶) extracellular matrix, involved cancer, melanoma brain proteoglycan 2 in endothelial growth metastasis [HGNC: 5273] FSTL1-follistatin-like 1 −1.8 Involved in the lung inhibits the invasion and [HGNC: 3972] (7.6 × 10⁻⁸) development metastasis CD274- PD-L1 molecule −1.9 Involved in the suppression of Associated with tumoral [HGNC: 17635] (3.3 × 10⁻⁴) immune response immune escape NID2- nidogen 2 −2.1 A basal lamina protein Tumor suppressor (osteonidogen) (1.8 × 10⁻⁶) [HGNC: 13389] GAS6- growth arrest- −1.7 AXL receptor tyrosine kinase Overexpressed in lung specific 6 [HGNC: 4168] (3.0 × 10⁻³) activation cancer GPIBA-glycoprotein Ib −1.7 A receptor for von Willebrandt Associated with cachexia (platelet), alpha (1.0 × 10⁻³) factor (VWF) in metastatic melanoma polypeptide [HGNC: 4439] IGFBP7- insulin-like −1.8 It is involved in IGF high It is associated with growth factor binding (2.1 × 10⁻⁵) affinity interaction and cell NSCLC progression protein 7 [HGNC: 5476] adhesion EXTRACELLULAR SPACE CCL24- chemokine (C-C  1.9 CHEMOTACTIC FOR Associated with poor motif) ligand 24 (3.0 × 10⁻⁴) RESTING T prognosis in hepatocellular [HGNC: 10623] LYMPHOCYTES AND carcinoma (HCC) and EOSINOPHILS colorectal cancer CCL28- chemokine (C-C  1.9 Involved in inflammatory Support cancer metastasis motif) ligand 28 (8.8 × 10⁻⁴) response [HGNC: 17700] SPINK1- serine peptidase  1.9 A serine protease inhibitor Associated with prostate inhibitor, Kazal type 1 (4.4 × 10⁻⁴) cancer [HGNC: 11244] PROC- protein C  1.8 involved in hemostasis, The expression is (inactivator of coagulation (1.2 × 10⁻³) inflammation and signal associated with an factors Va and Villa) transduction improved lung cancer [HGNC: 9451] prognosis SPINT1- serine peptidase  1.7 A serine protease inhibitor Associated with lung inhibitor, Kunitz type 1 (6.8 × 10⁻⁵) cancer malignant pleural [HGNC: 11246] effusion LGALS3- lectin,  1.6 Associated with cell adhesion, Involved in A549 cells, galactoside-binding, (1.6 × 10⁻⁴) cell activation and promoted CSC formation. soluble, 3 [HGNC: 6563] chemoattraction, cell growth Involved in involved in and differentiation, cell cycle, inflammation and fibrosis and apoptosis CX3CL1-chemokine (C-  1.6 Activates integrins and elicits Associated with cancer X3-C motif) ligand 1 (1.6 × 10⁻⁴) adhesive and migratory progression [HGNC: 10647] leukocytes functions IGFBP1- insulin-like −1.6 Improves and inhibits IGF a tumor growth inhibitor in growth factor binding (8.3 × 10⁻⁶) interaction with cells surface breast cancer cells protein 1 [HGNC: 5469] receptors MST1- macrophage −1.6 Hepatocyte growth factor-like Antiproliferative activity in stimulating 1 (hepatocyte (1.9 × 10⁻³) protein A549 cells growth factor-like) [HGNC: 7380] CPM- carboxypeptidase M −1.7 Presents in pneumocytes and Associated with poor [HGNC: 2311] (1.0 × 10⁻⁴) involved in EGFR activation prognosis in lung adenocarcinomas WISP2- WNT1 inducible −1.7 The CCN family of proteins Promotes a stem-like cell signaling pathway protein 2 (9.1 × 10⁻⁶) involved in cell adhesion, phenotype in breast cancer [HGNC: 12770] migration, proliferation, cells. Acts as a tumor differentiation suppressor in colorectal cancer IGFBP3- insulin-like −1.8 blocks the access of IGF-1, 2 Functions as a tumor growth factor binding (4.5 × 10⁻⁸) to IGF-1R suppressor protein 3 [HGNC: 5472] CELL MEMBRANE CLDN4- claudin 4  2.4 Involved in tight junction- Associated with a good [HGNC: 2046] (3.9 × 10⁻⁹) specific obliteration of the prognosis in NSCLC, SCC intercellular space. subgroups EMP1- epithelial  1.8 Involved in tight junction- Reduced expression membrane protein 1 (4.7 × 10⁻⁵) specific obliteration of the associated with lung cancer [HGNC: 3333] intercellular space. progression BAMBI- BMP and activin  1.7 Negatively regulates TGF-beta Involved in the suppression membrane-bound inhibitor (2.9 × 10⁻⁴) signaling of invasiveness [HGNC: 30251] CDH3- cadherin 3, type 1,  1.7 Cadherin protein related to Associated with expression P-cadherin (placental) (4.0 × 10⁻³) stem cells properties in lung cancer [HGNC: 1762] DSC2- desmocollin 2  1.6 Cadhcrin-type protein involved Reduced expression [HGNC: 3036] (1.4 × 10⁻⁵) in adjacent cells interaction associated with poor prognosis in pancreas, colorectal and esophageal squamous cell cancers TNS1- tensin 1 −1.6 Actin-binding protein, Involved in EMT, tumor [HGNC: 11973] (7.7 × 10⁻⁶) promotes motility invasion and metastasis CLMP- Coxsackie- and −1.7 Involved in cell-cell adhesion Associated with poor adenovirus receptor (9.1 × 10⁻⁴) prognosis (CXADR)-like membrane protein [HGNC: 24039] C5AR1 (CD88)- −1.7 Complement component 5a Associated with poor complement component 5a (4.0 × 10⁻³) receptor involved in prognosis in NSCLC receptor 1 [HGNC: 1338] inflammatory response. CNTNAP2-contactin −1.8 The protein of neurexin family, Associated with poor associated protein-like 2 (9.4 × 10⁻⁵) involved in cell adhesion. prognosis in breast cancer [HGNC: 13830] ITGA1 (CD49a)- integrin −1.9 Involved in cell-cell adhesion, Involved in lung subunit alpha 1 (1.1 × 10⁻⁵) inflammation and fibrosis lymphangioleiomyomatosis (LAM) invasiveness ACKR3- atypical −2.2 a receptor for chemokines Increased expression in chemokine receptor 3 (1.8 × 10⁻⁵) CXCL11 and CXCL12/SDF1 lung SCC [HGNC: 23692] EXTRACELLULAR MATRIX COL17A1 (BP180)-  2.1 involved in epidermal adhesion Underexpression in breast collagen, type XVII, alpha (3.0 × 10⁻⁷) cancer associated with poor 1 [HGNC: 2194] prognosis COL5A1- collagen, type V, −1.5 Belongs to type I collagen and ASSOCIATED WITH A alpha 1 [HGNC: 2209] (5.0 × 10⁻⁴) binds to DNA, heparan sulfate, RENAL CANCER POOR thrombospondin, heparin, and PROGNOSIS, GASTRIC, insulin BREAST CANCERS COL12A1- collagen, type −1.5 Interacts with type I collagen Associated with drug XII, alpha 1 [HGNC: 2188] (9.8 × 10⁻⁴) and the surrounding matrix resistance in ovarian cancer cell lines, breast cancer progression, colorectal cancer metastasis VCAN- versican −1.5 Involved in cells-extracellular, Associated with an [HGNC: 2464] (1.3 × 10⁻³) matrix interaction advanced disease SMOC1- SPARC related −1.6 A matricellular protein Increased in brain cancers. modular calcium binding 1 (3.7 × 10⁻⁴) interferes with growth factor Involved in angiogenesis. [HGNC: 20318] receptor signaling Interacts with NID2 VTN- vitronectin −1.6 A cell adhesion and spreading Not correlated with disease [HGNC: 12724] (1.0 × 10⁻²) factor progression COL4A2- collagen, type −1.8 The major structural Associated with lung IV, alpha 2 [HGNC: 2203] (1.1 × 10⁻⁶) component of glomerular cancer, melanoma brain basement membranes, fonning metastasis, gastric cancer a ‘chicken-wire’ meshwork together widi laminins, proteoglycans and entactin/nidogen FBN1- fibrillin 1 −1.7 Extracellular matrix Associated with an ovarian [HGNC: 3603] (2.0 × 10⁻³) glycoprotein serves as a cancer progress structural component BMPER- BMP binding −1.7 Inhibitor of BMP activity Associated with tumor endothelial regulator (4.2 × 10⁻³) growth. [HGNC: 24154] BMP2-bone morphogenetic −1.8 Implicated in the development Associated with tumor protein 2 [HGNC: 1069] (5.2 × 10⁻⁴) of bone and cartilage. Involved growth. in the hedgehog pathway, TGF beta signaling pathway activation GPC6- glypican 6 −1.8 extracellular matrix proteins, Involved in invasion of [HGNC: 4454] (9.6 × 10⁻⁵) breast cancer NLGN2- neuroligin 2 −1.8 Involved in cell-cell No direct association [HGNC: 14290] (1.4 × 10⁻⁶) interactions via its interactions reported with neurexin family members (see CNTNAP2) ADAMTS9- ADAM −2.2 Metalloproteinase and involved Inhibits angiogenesis and metallopeptidase with (2.1 × 10⁻⁵) in the transport from the tumor growth in ESCC and thrombospondin type 1 endoplasmic reticulum to the NPC motif, 9 [HGNC: 13202] Golgi apparatus COL4A1- collagen, type −2.2 The major structural Associated with lung IV, alpha 1 [HGNC: 2202] (9.6 × 10⁻⁷) component of glomerular cancer, melanoma brain basement membranes (GBM), metastasis, gastric cancer forming a ‘chicken-wire’ meshwork together with laminins, proteoglycans and entactin/nidogen ABI3BP (TARSH)- ABI −2.4 The cellular senescence-related Decreased expression is family, member 3 (NESH) (1.1 × 10⁻⁶) gene associated with lung cancer binding protein progression and metastasis [HGNC: 17265] EDIL3 (Del1)-EGF-like −2.5 Interacts with the αv/β3 ASSOCIATED WITH repeats and discoidin I-like (1.6 × 10⁻⁶) integrin receptor and promotes LUNG CANCER CELL domains 3 [HGNC: 3173] adhesion of endothelial cells. PROLIFERATION AND INVASION CCBE1- collagen and −2.7 Involved in angiogenesis A prognostic marker for calcium binding EGF (4.3 × 10⁻⁷) process gastrointestinal stromal domains 1 [HGNC: 29426] tumor progression TGFBI-Transforming −1.9 Involved in cell-collagen Associated with invasion, growth factor-beta-induced (1.5 × 10⁻⁵) interactions and cells adhesion signaling and ECM protein ig-h3 interaction in different [HGNC: 11771] types of cancer MMP2-Metalloproteinase 2 −2.9 Involved in angiogenesis, Associated with cancer (72 kDa type IV (6.9 × 10⁻⁶) tissue repair, tumor invasion, progression by ECM collagenase) [HGNC: 7166] inflammation, and degradation in different adierosclerotic plaque rupture types of tumor and degrading extracellular matrix proteins ENDOPLASMIC AND GOLGI LUMENS AGR3- anterior gradient 3  4.1 Required for calcium-mediated Associated with ovarian [HGNC: 24167] (1.33 × 10⁻⁶)  regulation (ER) cancer RYR1- ryanodine receptor  2.5 Ca²⁺ channel that mediates the Associated with breast 1 [HGNC: 10483] (5.6 × 10⁻³) release of Ca²⁺ from the cancer [HGNC: 22998] sarcoplasmic reticulum into the cytoplasm (ER/SR) NCK2- NCK adaptor  2.0 Adapter protein which Associated with ovarian protein 2 [HGNC: 7665] (2.04 × 10⁻⁶)  associates with tyrosine- cancer phosphorylated growth factor receptors or their cellular substrates (ER) SEC61G- Sec61 gamma  1.8 Protein translocation in the Associated with pediatric subunit [HGNC: 18277] (4.3 × 10⁻⁴) (ER). Ependymomas BACE1- beta-site APP- −1.5 Amyloid precursor protein May be involved in tumor cleaving enzyme 1 (2.2 × 10⁻³) (APP) protease angiogenesis [HGNC: 933] FOXRED2- FAD- −1.5 Functions in endoplasmic FOXRED2 is a dependent oxidoreductase (2.0 × 10⁻³) reticulum associated transcriptomic fingerprint domain containing 2 degradation of KRAS [HGNC: 26264] H6PD (GDH)- hexose-6- −1.6 Oxidizes hexose-6-phosphates Associated with breast phosphate dehydrogenase (1.3 × 10⁻⁴) and glucose cancer poor prognosis (glucose 1-dehydrogenase) [HGNC: 4795] ACAD10- acyl-CoA −1.7 Acyl-CoA dehydrogenase only No direct association dehydrogenase family, (1.6 × 10⁻³) active with R- and S-2-methyl- reported member 10 [HGNC: 21597] C15-CoA (mitochondria) TM4SF20- transmembrane −1.7 Polytopic transmembrane No direct association 4 L six family member 20 (1.26 × 10⁻⁸)  protein that inhibits reported [HGNC: 26230] intramembrane proteolysis (RIP) of CREB3L1 (ER) TMEM147-AS-TMEM147 −1.7 Antisense to transmembrane No direct association antisense RNA 1 (8.5 × 10⁻³) protein (ER) reported [HGNC: 51273] AHCYL2- −1.7 Regulating the No direct association adenosylhomocysteinase- (4.05 × 10⁻⁴)  sodium/bicarbonate reported like 2 [HGNC: 22204] cotransporter SLC4A4 activity and Mg²⁺⁻sensitivity (ER) ITPR1-inositol 1,4,5- −1.7 Intracellular channel mediating Associated with renal trisphosphate receptor, ripe (7.9 × 10⁻⁴) Ca²⁺ release from the ER upon cancer 1 [HGNC: 6180] stimulation by inositol 1,4,5- trisphosphate (ER) CHERP- calcium −1.7 Involved in Ca²⁺ homeostasis, Associated with homeostasis endoplasmic (7.05 × 10⁻⁴)  growth and proliferation neuroblastoma reticulum protein (ER) [HGNC: 16930] PTGS2 (COX-2)- −1.8 Converts arachidonate to Involved in hunor grow prostaglandin-endoperoxide (1.4 × 10⁻⁴) prostaglandin H2 and metastasis synthase 2 [HGNC: 9605] P4HA3- prolyl 4- −1.9 Involved in the post- Associated with breast hydroxylase, alpha (5.5 × 10⁻⁵) translational formation of 4- cancer progression polypeptide III hydroxy proline in -Xaa-Pro- [HGNC: 30135] Gly- sequences in collagens PPAP2B- phosphatidic −1.8 Catalyzes the conversion of Associated with non small acid phosphatase type 2B (1.31 × 10⁻⁶)  phosphatidic acid (PA) to cells lung carcinoma [HGNC: 9229] diacylglycerol and hydrolyzes lysophosphatidic acid (ER) CYP26B1- cytochrome −1.8 Involved in the metabolism of Associated with esophageal P450, family 26, subfamily (3.85 × 10⁻⁴)  retinoic acid (RA), (ER) squamous cell carcinoma. B, polypeptide 1 [HGNC: 20581] CLGN- calmegin −1.9 A chaperone for a range of Associated with breast [HGNC: 2060] (8.6 × 10⁻⁴) proteins (ER) cancer PCSK5- proprotein −2.3 Endoprotease activity protein Underexpressed in lung convertase subtilisin/kexin (2.7 × 10⁻⁶) cancer type 5 [HGNC: 8747] COX10-AS1- COX10 −2.1 Antisense to (ER) COX10 No direct association antisense RNA 1 (7.12 × 10⁻³)  protein, which converts reported [HGNC: 38873] protoheme IX and famesyl diphosphate to heme O. ABCC6- ATP-binding −2.3 Transports glutathione Associated with pancreatic cassette, sub-family C (1.4 × 10⁻³) conjugates as leukotriene-c4 carcinoma (CFTR/MRP), member 6 (LTC4) and N-ethylmaleimide [HGNC: 57] S-glutathione (ER). RIC3- RIC3 acetylcholine −2.7 Promotes functional expression No direct association receptor chaperone (1.6 × 10⁻³) of homomeric alpha-7 and reported [HGNC: 30338] alpha-8 nicotinic acetylcholine receptors at the cell surface (ER, Golgi) UGT1A7- UDP −3.5 UDPGT is important in the Associated with lung glucuronosyltransferase 1 (4.6 × 10⁻³) conjugation and subsequent cancer family, polypeptide A7 elimination of potentially toxic [HGNC: 12539] xenobiotics and endogenous compounds. This isoform has specificity for phenols (ER) CEMIP- cell migration −3.6 Mediates depolymerization of Associated with colorectal inducing protein, (1.06 × 10⁻⁸)  hyaluronic acid (HA) via the cancer hyaluronan binding cell membrane-associated [HGNC: 29213] clathrin-coated pit endocytic pathway (ER) FAM20A- family with −4.4 An allosteric activator of the Associated with cancer sequence similarity 20, (4.8 × 10⁻³) Golgi serine/threonine protein stem cells member A [HGNC: 23015] kinase FAM20C (ER, Golgi) UGT1A9-UDP −17.2  UDPGT is important in the Associated with glucuronosyltransferase 1 (9.8 × 10⁻⁴) conjugation and subsequent gastrointestinal cancer family, polypeptide A9 elimination of potentially toxic [Source: HGNC xenobiotics and endogenous Symbol; Acc: HGNC: 12541] compounds. This isoform has specificity for phenols (ER) ER AND MITOCHONDRIA KLK6- kallikrein-related  25.83 Serine protease (ER, Associated with NSCLC peptidase 6 [HGNC: 6367] (9.83 × 10⁻⁵)  mitochondria) SGK1- −1.7 Serine/threonine-protein kinase Associated with NSCLC serum/glucocorticoid (7.2 × 10⁻⁸) regulating a wide variety of ion regulated kinase 1 channels, transporters, cellular [HGNC: 10810] enzymes, transcription factors (ER, mitochondria) Mitochondria BIK- BCL2-interacting  2.1 Accelerates apoptosis by Associated with lung killer (apoptosis-inducing) (2.8 × 10⁻³) binding to anti- apoptosis cancer [HGNC: 1051] proteins Bcl-X(L), BHRF1 or Bcl-2 suppresses this death- promoting activity (mitochondria) ENDOG- endonuclease G  1.8 Involved in replication of Associated with lung [HGNC: 3346] (2.09 × 10−³)  mitochondrial DNA, as cancer AIF1 released from mitochondria in the time of apoptosis and is function, as endonuclease in Nucleus (mitochondria). CHCHD7- coiled-coil-  1.6 Unknown No direct association helix-coiled-coil-helix (1.48 × 10⁻³)  (mitochondria) reported domain containing 7 [HGNC: 28314] MYO19- mitochondrially −1.6 Actin-based motor Associated with encoded NADH (4.33 × 10⁻⁵)  molecule with ATPase glioma dehydrogenase 5 activity localized to the [HGNC: 7461] mitochondrion outer membrane, involved in the interaction of mitochondria with cytoskeleton (mitochondria) MT-ND5- mitochondrially −1.6 Subunit of the It may be associated encoded NADH (2.65 × 10⁻⁴)  mitochondrial respiratory with breast cancer dehydrogenase 5 chain NADH [HGNC: 7461] dehydrogenase (Complex I) ANXA10- annexin A10 −1.7 Ca²⁺ -dependent Associated with lung [HGNC: 534] (9.0 × 10⁻³) phospholipid binding cancer (Mitochondria) CYP24A1- cytochrome −1.9 Plays a role in It may be associated P450, family 24, subfamily (1.15 × 10⁻⁸)  maintaining Ca²⁺ with lung cancer A, polypeptide 1 homeostasis. [HGNC: 2602] (Mitochondria) MT-ND4L- −1.9 Subunit of the Associated with mitochondrially encoded (3.36 × 10⁻⁶)  mitochondrial respiratory childhood acute NADH dehydrogenase 4L chain NADH lymphoblastic [HGNC: 7460] dehydrogenase (Complex leukemia I) (Mitochondria) C10orf2 (TWINK)- −1.9 Involved in mitochondrial No direct association chromosome 10 open (6.5 × 10⁻⁴) DNA (mtDNA) reported reading frame 2 metabolism. Could [HGNC: 1160] function as an adenine nucleotide-dependent DNA helicase (mitochondria) STARD13- StAR-related −2.2 GTPase-activating protein It is known, as a tumor lipid transfer (START) (5.39 × 10⁻⁵)  for RhoA, and for Cdc42. suppressor in lung domain containing 13 Involved in lipid cancer [HGNC: 19164] binding(mitochondria) CPS1- carbamoyl- −4.8 Involved in the urea cycle Associated with lung phosphate synthase 1,  (7.9 × 10⁻¹⁸) of ureotelic animals, cancer mitochondrial removing excess [HGNC: 2323] ammonia from the cell (mitochondria)

TABLE 4 Transporters and metabolism related genes differentially expressed between si-NT- and si-hSMAC-A-treated A549 cells derived lung tumors Fold change Proposed function & Gene (Uniport accession) (p value) cellular localization Relation to cancer TRANSPORTERS SLC4A4- solute carrier family −3.3  Regulates bicarbonate Plays a role in growth 4 (sodium bicarbonate (3.1 × 10⁸)  influx/efflux at the basolateral and migration of colon cotransporter), member 4 membrane of cells and and breast cancer. [HGNC: 11030] intracellular pH. (Cell membrane) SLCO2B1- solute carrier −2.8  Mediates the Na+-independent Associated with prostate organic anion transporter (4.1 × 10¹⁰) transport of organic anions, cancer. family, member 2B1 taurocholate, the prostaglandins [HGNC: 10962] PGD2, PGE1, PGE2, leukotriene C4, thromboxane B2. (Cell membrane) SLC6A9- solute carrier family −1.7  Play a role in glycine transport Associated with Thyroid 6 (neurotransmitter transporter, (5.7 × 10⁻⁴) and thus in glycine regulation of cancer glycine), member 9 NMDA receptor-mediated [HGNC: 11056] neurotransmission. (Cell membrane) SLC24A1- solute carrier family −1.6  Controlling the calcium No direct association 24 (sodium/ potassium/calcium  (1 × 10⁻³) concentration of outer segments reported exchanger), member 1 during light and darkness and [HGNC: 10975] plays a key role in the process of light adaptation. (Cell membrane) SLC25A37- solute carrier −1.5  Mitochondrial iron transporter Associated with prostate family 25 (mitochondrial iron (1.2 × 10⁻⁴) mediates iron uptake in cancer transporter), member 37 developing erythroid cells and [HGNC: 29786] playing a role in heme biosynthesis, (IMM) KCNK1- potassium channel, 1.7 Contributes to passive Overexpressed in lung subfamily K, member 1 (1.1 × 10⁻⁷) transmembrane potassium cancer [HGNC: 6272] transport and regulation of the resting membrane potential. (Cell membrane, recycling endosome and cytoplasmic vesicle) SLC45A3- solute carrier family 1.8 H+/sucrose symporter slc45a3 as Up-regulated by 45, member 3 [HGNC: 8642] (9.4 × 10⁻⁴) an osmolyte transporter in the androgens and play a kidney, regulation of lipid role in prostate cancer metabolism in oligodendrocytes. malignancy (Cell membrane) KCNN4- potassium channel 1.8 Required for maximal calcium Overexpressed in ovarian calcium-activated channel, (6.8 × 10⁻⁵) influx and proliferation during cancer subfamily N, member 4 the reactivation of naive T-cells. [HGNC: 6293] (Cell membrane) GLTP- glycolipid transfer 1.8 Catalyzes the transfer of various Overexpressed in oral protein [HGNC: 24867] (1.4 × 10⁻³) glycosphingolipids between squamous cell carcinoma membranes SCNN1A- sodium channel, 1.9 Plays an essential role in Prognostic marker for non-voltage-gated 1 alpha (4.2 × 10⁻⁵) electrolyte and blood pressure pulmonary subunit [HGNC: 10599] homeostasis and taste perception. adenocarcinoma (Apical cell membrane) SLC44A4- solute carrier family 2.2 Choline and Thiamine Associated with prostate 44, member 4 [HGNC: 13941] (2.6 × 10⁻⁶) pyrophosphate (TPP) transporter and pancreatic cancers (Cell membrane) TMC8- transmembrane 2.4 Play a role as ion channel. Involved in EV-HPV channel-like 8 [HGNC: 20474] (5.8 × 10⁻⁷) (Endoplasmic reticulum oncogenicity and membrane) squamous cell carcinoma SLC9A3R2- solute carrier 2.5 Cation/proton antiporter and Associated widi breast family 9, subfamily A (NHE3, (6.3 × 10⁻⁷) scaffold protein in the plasma cancer cation proton antiporter 3), membrane. Acts as scaffold member 3 regulator 2 protein in the nucleus. [HGNC: 11076] (Endomembrane, nucleus) CRACR2A- calcium release 3.2 Acts as a cytoplasmic calcium- No direct association activated channel regulator 2A  (1 × 10⁻⁴) sensor and plays a key role in reported [HGNC: 28657] store-operated calcium entry in T-cells by regulating CRAC channel activation. (Cytoplasm) ANO1-anoctamin 1, calcium 3.4 A transepithelial anion transport Overexpressed in activated chloride channel (3.4 × 10⁻⁵) and smooth muscle contraction. different ty pes of cancer. [HGNC: 21625] (Cell membrane, Cytoplasm) TMC4- transmembrane 6.3 Play a role as ion channels. No direct association channel-like 4 [HGNC: 22998]  (6.2 × 10⁻¹²) (Membrane) reported ATP10B- ATPase, class V, 25.5  Catalyzes ATP-dependent Overexpressed type 10B [HGNC: 13543] (7.8 × 10⁻⁵) transport of aminophospholipids in lung adenocarcinoma and ensures the maintenance of and peripheral blood asymmetric distribution of cells phospholipids (cytoplasmic vesicles and ER membrane) METABOLISM RELATED ENZYMES PCK1- −6.9  Catalyzes the conversion of Low level expression phosphoenolpyruvatecarboxykinase  (2.3 × 10⁻¹¹) oxaloacetate to associated with 1 [HGNC: 8724] phosphoenolpyruvate. hepatocarcinogenesis (Cytoplasm) ADH4 - alcohol dehydrogenase −2.6  Catalyzes the reaction: Downregulated in 4 (class II) (4.2 × 10⁻⁴) An alcohol + NAD+ → an ovarian and liver cancer [HGNC: 252] aldehyde or ketone + NADH. (Cytoplasm) ADARB1- adenosine −2.1  Hydrolytic deamination of Associated with deaminase, RNA-specific, B1 (8.1 × 10⁻⁵) adenosine to inosine. (Nucleus) numerous carcinomas [HGNC: 226] and sarcomas ACAD 10- acyl-CoA −1.7 Associated with fatty acid beta Associated w ith reduced dehydrogenase family, member (1.6 × 10⁻³) oxidation. (Mitochondria) viability in melanoma 10, [HGNC: 21597] and pancreatic cancer cells H6PD - hexose-6-phosphate −1.6  Associated with glucose Associated with dehydrogenase [HGNC: 4795] (1.2 × 10⁻⁴) metabolic process. (Endoplasmic chemoresistance activity reticulum) CAD- carbamoyl-phosphate −1.6  Catalyzes the reaction 2 ATP + Associated with sy nthetase 2, aspartate (1.3 × 10⁻⁴) L-glutamine + HCO3— + H2O → colorectal, transcarbamylase, and 2 ADP + phosphate + L- prostate cancers dihydroorotase [HGNC: 1424] glutamate + carbamoyl phosphate. (Cytoplasm and nucleus) ACSL4-acyl-CoA synthetase −1.6  Activation of long-chain fatty Associated with breast, long-chain family member 4 (1.0 × 10⁻²) acids for both synthesis of colon, brain and [HGNC: 3571] cellular lipids, and degradation lung cancers via beta-oxidation DGKD-diacylglycerol kinase, −1.5  Involved in 1,2-diacyl-sn- Associated with delta 130 kDa [HGNC: 2851] (2.7 × 10⁻⁴) glvcerol phosphorylation prostate cancer FASN-fatty acid synthase −1.5  Catalyzes the formation of long- Associated with [HGNC: 3594] (3.3 × 10⁻⁴) chain fatty acids from acetyl- lung cancer and others CoA, malonyl-CoA and NADPH ORMDL2-sphingolipid 1.5 Negative regulator of No direct association biosynthesis regulator 2 (4.0 × 10⁻³) sphingolipid synthesis reported [HGNC: 16037] CANT1- calcium activated 1.5 Nucleotidase involved in UDP, Associated with nucleotidase 1 [HGNC: 19721] (4.0 × 10⁻⁴) GDP, UTP, GTP melanoma dephosphorylation. (Golgi, Endoplasmatic reticulum) CMAS- cytidine 1.5 Involved in the pathway N- Associated with breast monophosphate N- (7.4 × 10⁻⁴) acetylneuraminate metabolism. cancer acetylneuraminic acid (Nucleus) synthetase [HGNC: 18290] GPT2- glutamic pyruvate 1.5 Formation of pyruvate and Associated with colon, transaminase (alanine (1.4 × 10⁻³) glutamate by transamination liver cancers. aminotransferase) 2 between alanine and 2- [HGNC: 18062] oxoglutarate. (Mitochondria) MGAT4B- mannosyl (alpha- 1.5 Glycosyltransferase involved in Associated with mouse 1,3-)-gly coprotein beta-1,4-N- (6.7 × 10⁻⁴) transfer GlcNAc to the core carcinogen-induced acetylglucosaminyltransferase, mannose residues. (Golgi) hepatocarcinoma. isozyme B [HGNC: 7048] ST3GAL4- ST3 beta- 1.5 Involved in protein Associated with gastric galactoside alpha-2,3- (4.5 × 10⁻³) glycosylation. (Golgi) carcinoma. sialyltransferase 4 [HGNC: 10864] AGPAT2- l-acylglycerol-3- 1.6 Converts lysophosphatidic acid Upregulated in breast phosphate O-acyltransferase 2 (8.4 × 10⁻⁵) (LPA) into phosphatidic acid. and cervical cancer. [HGNC: 325] (Endoplasmic reticulum membrane) GALNT5- 1.6 Involved in protein Associated with polypeptide N- (1.7 × 10⁻⁵) glycosylation. (Golgi) hepatoblastoma. acetylgalactosaminyltransferase 5 [HGNC: 4127] GALNT12- 1.6 Involved in protein Associated with breast, polypeptide N- (3.3 × 10⁻⁴) glycosylation. (Golgi) colorectal cancers. acetylgalactosaminyltransferase 12 [HGNC: 19877] ST6GALNAC1- (alpha-N- 1.6 Involved in protein Associated with acetyl-neuraminy1-2,3-beta- (6.2 × 10⁻⁴) glycosylation. (Golgi) esophageal squamous galactosyl-1,3)-N- cell carcinoma and acetylgalactosaminide alpha- prostate cancer. 2,6-sialyltransferase 1 [HGNC: 23614] PLCB4 - phospholipase C, beta 1.7 Involved in inositol phosphate Biomarker for uveal 4 [HGNC: 9059] (9.2 × 10⁻⁴) metabolic process. (Cytosol, melanoma. Nucleus, smooth Endoplasmic reticulum) BLVRA - biliverdin reductase 1.7 Oxidation of bilirubin using Overexpressed in liver A [HGNC: 1062] (2.1 × 10⁻³) NAD(P) to biliverdin. cancer. (Cytoplasm) GCNT3- glucosaminvl (N- 1.7 Involved in carbohydrate Associated with acetyl) transferase 3, mucin (1.0 × 10⁻²) metabolic process. (Golgi) pancreatic, colon cancer. type [HGNC: 4205] ADI1 - acireductone 1.8 Formation of formate and 2-keto- Downregulated in dioxygenase 1 [HGNC: 30576] (1.8 × 10⁻⁴) 4-mediyldiiobutyrate. (Cytosol, prostate cancer. Nucleus and Cell membrane) FUT6- 1.8 Involved in L-fucose catabolic Associated with Fucosyl transferase 6 (alpha (1.5 × 10⁻³) process attenuation of EGFR (1,3) fucosyltransferase) (Golgi) signaling and invasivity. [HGNC: 4017] LIPH - lipase, member 1.9 Hydrolyzes specifically Overexpressed in lung [HHGNC: 18483] (3.1 × 10⁻³) phosphatidic acid (PA) to and breast cancer. produce 2-acyl lysophosphatidic acid (LPA) and fatty acid. (Membrane) GALNT6- 1.9 Involved in O-glycan processing Associated with polypeptide N-  (1.8 × 10−⁴) (Golgi) pancreatic, breast acetylgalactosaminyl cancers. transferase 6 [HGNC: 4128] CDA - cytidine deaminase 2.0 Cytidine deaminase. (Cytosol, Overexpressed in cancer [HGNC: 1712] (1.1 × 10⁻³) extracellular region) FAXDC2- fatty acid 2.1 Involved in fatty acid Reduced expression is hydroxy lase domain containing (5.7 × 10⁻⁵) biosynthetic process. associated with acute 2 [HGNC: 1334] (Endoplasmatic reticulum) myeloid leukemia and acute megakaryoblastic leukemia. B3GNT6- UDP-GlcNAc: 2.1 Involved in Associated with prostate betaGal beta-1,3-N- (1.6 × 10⁻⁴) glucuronosyltransferase activity. cancer. acetylglucosaminyltransferase 6 (Golgi) (core 3 synthase) [HGNC: 24141] ENTPD8 - ectonucleoside 2.7 Involved in purine and May be involved in the triphosphate (2.1 × 10⁻³) pyrimidine metabolism. (Cell chemical formation of diphosphohydrolase 8 membrane) DNA adducts. [HGNC: 24860] FUT3- fucosyltransferase 3 2.7 Involved in oligosaccharide Associated with (galactoside 3(4)-L- (2.9 × 10⁻⁷) biosynthetic process. (Golgi) metastasis and survival fucosyltransferase, Lewis blood rate group) [HGNC: 4014] CYB5R2 -cytochrome b5 2.8 Involved in desaturation and Act as a tumor reductase 2 [HGNC: 24376]  (3 × 10⁻⁴) elongation of fatty acids, suppressor in cholesterol biosynthesis, drug nasopharyngeal metabolism. (Cytosol, Nucleus, carcinoma smooth ER) DHRS9 - dehydrogenase/ 2.8 Involved in retinol metabolic Downregulated in reductase (SDR family) (5.6 × 10⁻⁴) process, colorectal cancer member 9 [HGNC: 16888] (Endoplasmic reticulum) SDR16C5- short chain 3.0 Involved in the oxidation of No direct association dehydrogenase/reductase family (1.1 × 10⁻⁴) retinol to retinaldehyde. reported 16C, member 5 (Endoplasmic reticulum) [HGNC: 30311] STARD10 - StAR-related lipid 3.7 Involved in phospholipid Associated with breast transfer (START) domain  (1.1 × 10⁻¹³) transport. (Cytosol, Nucleus) cancer containing 10 [HGNC: 10666] PADI1- peptidyl arginine 3.8 Deamination of arginine Involve in tumor deiminase, type I (2.1 × 10⁻³) residues. progression [HGNC: 18367] (Cytosol, Extracellular exosome) FAR2- fatty acyl CoA 4.1 Catalyzes the reduction of fatty No direct association reductase 2 [HGNC: 25531] (1.5 × 10⁻⁵) acyl-CoA to fatty alcohols reported DGAT2- diacylglycerol O- 4.9 Catalyzes the terminal step in Associated with acyltransferase 2 (2.5 × 10⁻⁴) triacylglycerol synthesis using Hepatocarcinoma [HGNC: 16940] diacylglycerol and fatty acyl CoA ELOVL3-fatty acid elongase 3 7.4 Catalyzes the long-chain fatty No direct association [HGNC: 18047] (1.0 × 10⁻³) acids elongation toward C18 reported acyl-CoAs ELOVL4 fatty acid elongase 4 145.2  Catalyzes the long-chain fatty Hypermethylated in [HGNC: 18047]  (6.2 × 10⁻¹⁷) acids elongation, elongates C24:0 pancreas, colorectal and C26:0 acyl-CoAs carcinoma REDOX STATE REGULATION NOS1-nitric oxide synthase, −5.9  Produces nitric oxide (NO), Abundant in low- neuronal [HGNC: 7872] (1.6 × 10⁻⁶) which is a ROS, neurotransmitter differentiated, breast and angiogenesis regulator gynaecological, central nerve system cancer and NSCLC SOD2- superoxide dismutase −1.9  Inactivates ROS, as superoxide Increased expression in [Mn], mitochondrial (3.7 × 10⁻⁵) anion radicals prostate, lung and colon [HGNC: 11180] cancer GSTP1- glutathione S- −1.6  Conjugates reduced glutathione Associated with lung transferase pi 1 [HGNC: 4638] (2.4 × 10⁻³) to a wide number of exogenous cancer and endogenous hydrophobic electrophiles (mitochondria) TXN-Thioredoxin 2.1 Involved in redox reactions Prognostic biomarker in [Source: HGNC (1.8 × 10⁻⁴) through the reversible oxidation NSCLC and breast Symbol; Acc: HGNC: 12435] of dithiol to a disulfide cancer PXDN-peroxidasin homolog 3.3 Participate in H₂O₂ metabolism Involved in melanoma [HGNC: 14966] (5.1 × 10⁻⁸) and peroxidative reactions invasion. The decreased expression is observed in myeloid leukaemia

TABLE 5 List of selected genes associated with Inflammation differentially expressed between si-NT- and si-hSMAC-A-treated A549 cells-derived tumors, NGS analysis Fold change Proposed function & Gene (Uniport accession) (p value) cellular localization Relation to cancer Inflammatory ligands CCL24- chemokine (C-C motif)  1.9 CHEMOTACTIC FOR Associated with poor ligand 24 [HGNC: 10623] (3.0 × 10⁻⁴) RESTING T prognosis in HCC and LYMPHOCYTES AND colorectal cancer EOSINOPHILS CCL28- chemokine (C-C motif)  1.9 Involved in inflammatory Support cancer metastasis ligand 28 [HGNC: 17700] (8.8 × 10⁻⁴) response PROC- protein C (inactivator of  1.8 involved in hemostasis, The expression is coagulation factors Va and (1.2 × 10⁻³) inflammation and signal associated with an VIIIa) [HGNC: 9451] transduction improved lung cancer prognosis CX3CL1-chemokine (C-X3-C  1.6 Activates integrins and Associated with cancer motif) ligand 1 [HGNC: 10647] (1.6 × 10⁻⁴) elicits adhesive and progression migratory leukocytes functions TNFAIP6 (TSG6)- −1.6 Interacts with ECM proteins Associated with poor tumor necrosis factor, alpha- (2.2 × 10⁻³) during inflammation and prognosis induced protein 6 tumorigenesis [HGNC: 11898] C5- complement component 5 −1.7 Involved in late complement Associated with a [HGNC: 1331] (1.0 × 10⁻²) components formation C5- favorable C9 and inflammation microenvironment for progress cancer progression GAS6- growth arrest-specific 6 −1.7 AXL receptor tyrosine kinase Overexpressed in lung [HGNC: 4168] (3.0 × 10⁻³) activation cancer TNFSF14 (LIGHT)- −1.8 Involved as a costimulatory TNFSF14 is involved in tumor necrosis factor (1.8 × 10⁻³) factor in anticancer anticancer immune- superfamily, member 14 lymphocytes cytotoxic stimulatory activity [HGNC: 11930] activity CD274-(PD-L1) molecule −1.9 A costimulatory molecule, Associated with a more [HGNC: 17635] (3.3 × 10⁻⁴) involved in the inhibition of aggressive nsclc T-cells proliferation and cytokine production IL6- interleukin 6 −2.5 Involved in inflammatory Over-expressed in [HGNC: 6018] (1.5 × 10⁻⁶) response NSCLC RECEPTORS AND CO-RECEPTORS IL1R1- interleukin 1 receptor, −1.6 Receptor for IL1A, IL1B and Associated with breast type I [HGNC: 5993] (4.0 × 10⁻⁴) IL1RN, mediates NF-kappa- cancer cells invasivity B and MAPK activation IL18BP- interleukin 18 binding −1.6 Interacts with IL-18, inhibits Produced in the ovarian protein [HGNC: 5987] (1.0 × 10⁻²) its activity and Th1 immune cancer microenvironment response to regulate immune response IL27RA- interleukin 27 −1.6 Receptor for IL27, acts Resulting in the receptor, alpha [HGNC: 17290] (1.0 × 10⁻²) through STAT3 and STAT1 promotion of tumor growth OSMR- oncostatin M receptor −1.7 Binds IL31 together with Associated with poor [HGNC: 8507] (6.7 × 10⁻⁶) IL31RA to activate STAT3 prognosis in cervical squamous cell carcinoma TLR3- toll-like receptor 3 −1.7 A nucleotide-sensing TLR Associated with lung [HGNC: 11849] (5.0 × 10⁻³) activated by double-stranded metastasis by neutrophil RNA, leading to NF-kappa-B activation activation MRC2 (ENDO180)- mannose −1.7 Involved in the remodeling Associated with prostate, receptor, C type 2 (3.6 × 10⁻³) of ECM cooperating with the breast cancers and [HGNC: 16875] MMPs metastasis C5AR1 (CD88)-complement −1.7 Receptor for the chemotactic Associated with poor component 5a receptor 1 (4.0 × 10⁻³) and inflammatory peptide prognosis [HGNC: 1338] anaphylatoxin C5a LBP-lipopolysaccharide binding −2.1 Binds to LPS and promotes It was not changed in lung protein [HGNC: 6517] (1.2 × 10⁻⁴) the cytokines release adenocarcinoma ACKR3- atypical chemokine −2.2 a receptor for chemokines Increased expression in receptor 3 [HGNC: 23692] (1.8 × 10⁻⁵) CXCL11 and CXCL12/SDF1 lung SCC CYTOSOLIC MOLECULES CREB3L3- cAMP responsive 2.0 Transcription factor No direct association element binding protein 3-like 3 (4.3 × 10⁻⁴) activates expression of acute reported [HGNC: 18855] phase response (APR) genes in inflammatory response IRF6- interferon regulatory 1.6 DNA-binding transcriptional Involved in tumor factor 6 [HGNC: 6121] (1.0 × 10⁻³) activator suppression and SCCs differentiation. PTGS2 (Cox-2)- prostaglandin - −1.8 Converts arachidonate to Involved in tumor grow endoperoxide synthase 2 (1.4 × 10⁻⁴) prostaglandin H2 and metastasis (prostaglandin G/H synthase and cyclooxygenase) [HGNC: 96051

Example 8: Ultrastructure and Lipid Synthesis in si-NT-TTs and si-hSMAC-A-TTs

As SMAC silencing resulted in morphological changes (FIG. 7 ), the sub-cellular ultrastructure of si-NT-TTs and si-hSMAC-A-TTs were analyzed using transmission electron microscopy (TEM) (FIGS. 10D, 12A). In si-NT-TTs, a massive amount of intracellular vesicles of different sizes and densities, such as lysosomes and large vesicles containing surfactant-accumulating lamellar bodies were seen. Such vesicles were not observed in the tumors where hSMAC/Diablo was silenced (si-hSMAC-A-TTs) (FIG. 10D, 12A).

In addition, in si-NT-TTs, the major DNA form in the nucleus is darkly staining heterochromatin, while in si-SMAC-TTs, the DNA is mainly found as euchromatin and not readily stained (FIGS. 10D, 12A, B). Interestingly, euchromatin is prevalent in cells that are active in the transcription of many genes, while heterochromatin is most abundant in cells that are less active. This may be associated with cell differentiation processes. Moreover, the sizes of nuclei in si-hSMAC-A-TTs are almost twice those in si-NT-TTs and showed lower chromatin staining (FIG. 10D, 12A, B). The large nuclei in si-NT-TTs could result from membrane fluidity and/or osmolality changes, as reflected in the modified expression of transporters (FIG. 11A, Table 4). Changes in the expression of genes associated with cell membrane, exosomes, and ER- and Golgi-related proteins (FIG. 11A, B) and in cell ultrastructure (FIG. 10D, E), are summarized in a schematic model (FIG. 12C).

The amounts of total phospholipids and PC in si-NC-TTs and si-SMAC-A-TTs lipid extracts were analyzed (FIG. 10F). Total phospholipids and PC were decreased by 47% and 37%, respectively, in si-SMAC-A-TTs.

These results are in agreement with the findings that SMAC/Diablo silencing resulted in alterations in the expression levels of genes associated with the transport, synthesis and regulation of lipids (FIG. 10C, Table 4). Therefore, using q-PCR, the levels of genes encoding enzymes associated with diacylglycerol (DAG) synthesis, such as glycerol kinase (GK), and the mitochondrial proteins glycerol-3-phosphate acyltransferase 1 and 4 (GPAM1, GPAM4) were analyzed. All were found to be decreased in si-SMAC-TTs (FIG. 10F). In addition, levels of mRNA encoding enzymes involved in PC synthesis were also decreased (FIG. 10F), whereas those encoding other enzymes associated with PC synthesis from phosphatidylethanolamine, namely phosphatidylethanolamine N-methyltransferase (PEMT), and choline/ethanolamine kinase A (CHKA), cholinephosphotransferase 1 (CHPT1) and phospholipase A2 (PLA2G1B), were increased. These results are presented in the PC and DAG synthesis pathways depicted in FIG. 10G.

Example 9: SMAC/Diablo Interacting Peptides

A network of proteins interacting with SMAC/Diablo (FIG. 15A) was identified using Thebiogrid database for protein-protein interactions (thebiogrid.org), based on the following methods to define interactions: Two hybrid analysis;

-   -   Affinity capture-Western blots;     -   Affinity capture-MS;     -   Co-crystal structure     -   Biochemical activity     -   Protein-peptide interaction;     -   Förster resonance energy transfer

Fourteen (14) proteins were selected as being associated with SMAC/Diablo, all of human (Homo sapiens) origin:

-   1. XIAP: X-linked inhibitor of apoptosis Protein (NP_001158.2;     Uniprot-P98170) -   2. HTRA2: HtrA serine peptidase 2 Protein (NP_037379.1;     Uniprot-O43464) -   3. BIRC2: Baculoviral IAP repeat containing 2 Protein (NP_001157.1;     Uniprot-Q13490) -   4. CD40: Tumor necrosis factor receptor superfamily member 5     (NP_001241.1; Uniprot-P25942) -   5. TRAF2: TNF receptor associated factor 2 Protein (NP_066961.2;     Uniprot-Q12933) -   6. UBE2K: Ubiquitin conjugating enzyme E2 K Protein (NP_005330.1;     Uniprot-P61086) -   7. NR4A1: Nuclear receptor subfamily 4 group A member 1 Protein     (NP_001189163.1; Uniprot-P22736) -   8. MAML2: Mastermind like transcriptional coactivator 2 Protein     (NP_115803.1; Uniprot-Q8IZL2) -   9. ARNT: Aryl hydrocarbon receptor nuclear translocator isoform 1     Protein (NP_001659.1; Uniprot-P27540) -   10. BIRC5: Baculoviral TAP repeat containing 5 Protein (NP_001159.2;     Uniprot-O15392) -   11. AREL1: Apoptosis resistant E3 ubiquitin protein ligase 1 Protein     (NP_001034568.1; Uniprot-O15033) -   12. GFER: Growth factor, augmenter of liver regeneration Protein     (NP_005253.3; Uniprot-P55789) -   13. MTFR1: Mitochondrial fission regulator 1 Protein (NP_055452.3;     Uniprot-Q15390) -   14. GMPPB: GDP-mannose pyrophosphorylase B Protein (NP_037466.2;     Uniprot-Q9Y5P6).

A custom glass-bound peptide array consisting of 768 overlapping peptides (of 20-25 amino acid length) derived from the above-selected proteins was prepared by Intavis, Bioanalytical instruments, Kolen, Germany.

The peptide array was incubated overnight at 4° C. with purified SMAC (0.8 μM) and then blotted with anti-SMAC antibodies (1:2000) and incubated for additional 4 h at 4° C. followed by 2 h incubation with HRP-conjugated anti-mouse IgG and detection using the EZ-ECL chemiluminescence detection kit as described hereinabove.

Dark spots, marked with their location on the peptide array, represent binding of SMAC to peptides derived from the SMAC-interacting proteins (FIG. 15B). The peptide origin, name and SEQ ID NOs. are presented in Table 6 below.

TABLE 6 Peptides derived from proteins associated with SMAC/Diablo that interacted with SMAC/Diablo SMAC/ Peptide Diablo designation inter- (Spot SEQ acting location ID protein FIG. 15) Peptide Sequence NO. BIRC5 1H13 SGCAFLSVKKQFEELTLGEFLKLD 46 UBE2K 2C18 VRFITKIWHPNISSVTGAICLDILK 47 BIRC2 1G12 LIRKNRMALFQQLTCVLPILDNLLK 48 1G13 FQQLTCVLPILDNLLKANVINKQEH 49 IE23 SASLGSTSKNTSPMRNSFAHSLSPT 50 1G18 LVKGNAAANIFKNCLKEIDSTLYKN 51 1G21 FVDKNMKYIPTEDVSGLSLEEQLRRL 52 TRAF2 1I23 MAAASVTPPGSLELLQPGFSKTLLGTK 53 1J20 DGCGKKKIPREKFQDHVKTCGKCRV 54 1K16 AGRIPAIFSPAFYTSRYGYKMCLRI 55 1K20 HLSLFFVVMKGPNDALLRWPFNQKV 56 MAML2 2D9 GAGLLGGGSVTPRVHSAIVERLRAR 57 2G8 QQQQQQQPSSQPAQSLPSQPLLRS* 58 2G9 SSQPAQSLPSQPLLRSPLPLQQKLLL 59 ARNT 2I14 MAATTANPEMTSDVPSLGPAIASGN 60 2J5 VSHMKSLRGTGNTSTDGSYKPSFLT 61 2J14 DVDKLREQLSTSENALTGRILDLKT 62 NR4A1 1M17 GDNASCQHYGVRTCEGCKGFFKRTV 63 1N22 ASCLKEHVAAVAGEPQPASCLSRLL 64 1N23 AVAGEPQPASCLSRLLGKLPELRTL 65 CD40 1I13 LVVQQAGTNKTDVVCGPQDRLRALV 66 HTRA2 1C9 ALGGIRWGRRPRLTPDLRALLTSGT 67 *Letter marked in italic represent overlapping sequence within SEQ ID NO: 58 and SEQ ID NO: 59.

Example 10: SMAC/Diablo Specific Interaction with Peptides Derived from SMAC/Diablo-Interacting Proteins

The effect of peptide 2C18 (SEQ ID NO:47) derived from the SMAC/Diablo interacting proteins, Ubiquitin conjugating enzyme E2 K Protein (UBEK2); and of peptide 1G12 (SEQ ID NO:48) derived from Baculoviral IAP repeat containing 2 Protein (BIRC2) on SMAC/Diablo capability to interact with these and other peptides was examined.

The glass-bound peptide array described hereinabove was used. SMAC/Diablo (0.8 μM) was incubated with each of the peptides—2C18 (2.4 μM) and 1G12 (2.4 μM) for 2 hr at 24° C. and then incubated with the peptide array for 4 h at 4° C. Then the slides were washed and SMAC/Diablo antibodies (1:2000) were added, followed by incubation with HRP-conjugated anti-mouse IgG after which chemiluminescent spots were detected. Corresponding glass-bound peptide array incubated overnight with 0.8 μM free SMAC/Diablo, blotted with the same concentration of SMAC/Diablo antibodies followed by incubation with HRP-conjugated anti-mouse IgG served as a control. As expected, pre-incubation of SMAC/Diablo with peptide 2C18 or peptide 1G12 significantly decreased or even prevented the interaction of SMAC/Diablo with the corresponding peptides, as the binding site is already occupied by the free peptide pre-incubated with SMAC/Diablo. This is indicated by the decreased intensity or disappearance of chemiluminescence in the peptide spot position compared to the control (FIG. 16 and FIG. 17 , respectively). Moreover, pre-incubation of SMAC/Diablo with peptide 2C18 decreased SMAC/Diablo interaction with the array-bound peptides 1M17 and 1N23 derived from Nuclear receptor subfamily 4 group A member 1 Protein (NR4A1) and peptide 1K20 derived from TNF receptor associated factor 2 Protein (TRAF2) (FIG. 16B, eliminated spots are circled). Pre-incubation of SMAC/Diablo with peptide 1G12 significantly reduced SMAC/Diablo interaction with 1G12 and also the interaction with peptide 1G13, also derived from BIRC2 and having overlapping sequence with peptide 1G12, but also with peptide 1H13, derived from Baculoviral IAP repeat containing 5 Protein (BIRCS) and peptide 2D9, derived from Mastermind like transcriptional coactivator 2 Protein (MAML2) (FIG. 17B, eliminated spots are circled).

Example 11: Cell Growth Inhibition by Peptides of the Invention

Considering the presence of the overexpressed SMAC/Diablo in the mitochondria intermembrane space and in the nucleus it is important to target SMAC/Diablo interacting peptide to these compartments, facilitating the cellular uptake and nucleus and/or mitochondria localization of the peptides of the present invention is of significant importance for the therapeutic use of the peptides of the invention. Several conjugates of peptides of the invention fused to cell- and nucleus or mitochondria penetrating peptide were designed (Table 7 below).

The tetrapeptide Arg-D-Arg-Arg-Lys (Cindy A P et al. 2010. Bioorganic & Medicinal Chemistry 18:3564-3569) was used to facilitate cellular uptake and nuclear localization. The peptide is designated herein cell/nucleus penetrating peptide (nuCPP, SEQ ID NO:71).

The tetrapeptide D-Arg-Dmt-Orn-Phe, wherein Dmt=2,6-dimethyl-L-tyrosine, (Carmine Pasquale Cerrato, et al. 2015. The FASEB Journal, 29(11): 4589-4599), was used to facilitate cellular uptake and mitochondria localization. The peptide is designated herein cell/mitochondria penetrating peptide (mtCPP, SEQ ID NO:72)

A peptide comprising transferrin-receptor binding domain (Tf) having the sequence His-Ala-Ile-Tyr-Pro-Arg (SEQ ID NO:80 and a peptide comprising the Drosophila antennapedia (ANTP) domain having the sequence Met-Arg-Gln-Ile-Lys Ile-Trp-Phe-Gln-Asn-Arg-Arg-Met-Lys-Trp-Lys (SEQ ID NO:81) each was used to facilitate uptake of the peptide through the cell plasma membrane and into the cytosol.

TABLE 7 Examined peptide conjugates Conjugate description Targeted to SEQ ID NO. 1H13-nuCPP Nucleus 69 1H13-mtCPP-NH₂ Mitochondria 73 1G12-nuCPP Nucleus 70 nuCPP-1G12 Nucleus 71 mtCPP-2C18 Mitochondria 74 ANTP-2C18 Cytosol 75 TF-1G12 Cytosol 76

A549 cells were seeded in 96-well plate (5000 cells/well). After 24 h cells were incubated with each of the examined peptides at a concentration of 5, 10, or 30 μM for 48 h in a serum (10%) containing medium or for 24 h in a serum-free medium. Then, cells were washed with PBS, fixed with 10% trichloroacetic acid, and analyzed for cell growth using the SRB method described herein above. Cell growth with no addition of a peptide was taken as a control (100% cell growth). Table 8 presents the cell growth in the presence of the peptide as % of control. Results are the mean±SD (n=3).

TABLE 8 Effect of cells treatment with peptides on cell growth Cell penetrating Concentration Cell growth, peptide Targeted to μM % of control Control 0 100 1H13-nuCPP Nucleus 5 92 ± 0.018 1H13-nuCPP Nucleus 10 57 ± 0.013 1H13-nuCPP Nucleus 30 30 ± 0.009 1H13-mtCPP-NH₂ Mitochondria 5 85 ± 0.022 1H13-mtCPP-NH₂ Mitochondria 10 60 ± 0.018 1H13-mtCPP-NH₂ Mitochondria 30 49 ± 0.014 1G12-nuCPP Nucleus 5 109 ± 0.013  1G12-nuCPP Nucleus 10 76 ± 0.024 1G12-nuCPP Nucleus 30 39 ± 0.013 nuCPP-1G12 Nucleus 5 96 ± 0.012 nuCPP-1G12 Nucleus 10 72 ± 0.01  nuCPP-1G12 Nucleus 30 66 ± 0.009 Tf- 1G12 Cytosol 5 99 ± 0.004 Tf- 1G12 Cytosol 10 98 ± 0.005 Tf- 1G12 Cytosol 30 99 ± 0.005 mtCPP-2C18 Mitochondria 5 89 ± 0.005 mtCPP-2C18 Mitochondria 10 74 ± 0.004 mtCPP-2C18 Mitochondria 30 59 ± 0.004 ANT-2C18 Cytosol 5 127 ± 0.006  ANT-2C18, Cytosol 10 145 ± 0.0162 ANT-2C18 Cytosol 30 97 ± 0.011

Table 8 clearly demonstrates that peptides derived from proteins interacting with SAMC/Diablo, shown herein to bind SMAC/Diablo, when targeted to the nucleus or the mitochondria significantly inhibit cell proliferation. These results indicate that the interaction of selected peptides with SMAC/Diablo under non-apoptotic conditions resulted in inhibition of the non-apoptotic function of SMAC/Diablo, leading to inhibited cell growth.

Example 12: Interaction of SMAC/Diablo with Phosphatidylserine Decarboxylase (PSD/PISD)

Phosphatidylserine decarboxylase or SMAC/Diablo expressing vector was expressed in Escherichia coli BL21 cells. Bacteria were grown at 37° C. to reach absorbance at 600 nm of 0.4, after which expression was induced with isopropyl β-D-1 thiogalactopyranoside. PSD was purified by chromatography using DEAE-cellulose column and eluted with NaCl. SMAC/Diablo was purified using nickel-nitrilotriacetic acid resin and eluted using imadazol. Representing results of the purified SMAC/Diablo and PSD are shown in FIG. 18A.

PSD activity was analyzed by following the formation of phosphatidylethanolamine (PE) analyzed as described hereinabove for lipids extracted from xenograft tumors. As is demonstrated in FIG. 18B, the purified enzyme was active. Purified SMAC was fluorescently labeled using the NanoTemper BLUE protein-labeling kit. Thermophoresis was measured using a Monolith-NT115 apparatus. As is demonstrated in FIG. 18C, SMAC/Diablo binds to PSD with a high affinity with Kd of 100 nM. The present invention shows that upon SMAC deletion, PL and PC levels were decreased 2-fold, while PE levels increased 2-fold. One of the key proteins in PL synthesis is phosphatidylserine decarboxylase (PSD), a mitochondrial enzyme which catalyzes the formation of PE from phosphatidylserine (PS). PS is produced in the ER from PC and PE by PSS1 and and PSS2, respectively (FIG. 18D). Without wishing to be bound by any specific theory or mechanism of action, the increase in PE suggests activation of mitochondrial PSD in the absence of SMAC and thus, depleting the ER from PS and PC, thus interfering with phospholipids synthesis essential for the growth of cancerous cells.

Example 13: Inhibition of Tumor Growth in Mice by the Peptides of the Invention

The effect of selected peptides, particularly the peptide conjugates of SEQ ID NOs” 69-71 and 72-74 on sub-cutaneous (s.c) tumors is examined.

A549 (5×10⁶) or diffuse large B-cell lymphoma (DLBCL) HT (ACC-567) cells (3×10⁶) are injected sub-cutaneously into the hind leg flanks of eight week-old athymic male nude mice (Envigo). When tumor size reaches 50-100 mm³, the mice are grouped and treated by intra-tumoral injection of a buffer (HBSS) or with the selected peptide/peptide conjugate to a final concentration of 30 to 60 μM. Mice are sacrificed when tumors volumes reach 10-15% of the mouse weight. Tumors are then excised; half of each tumor is fixed in 4% buffered formaldehyde, paraffin-embedded and processed for IHC, and the second half is frozen in liquid nitrogen for immunoblotting and qPCR analyses. Tumor sections are analyzed for: (a) proteins related to lipid metabolism; (b) cancer cell proliferation by staining for the proliferation factor Ki-67 using specific antibodies; (c) tissue morphology using H&E and Sirius Red staining to monitor stromal activity and anti-CD31 antibody staining for evaluating angiogenesis; and (d) apoptosis using the TUNEL assay.

The foregoing description of the specific embodiments will so fully reveal the general nature of the invention that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without undue experimentation and without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The means, materials, and steps for carrying out various disclosed functions may take a variety of alternative forms without departing from the invention. 

The invention claimed is:
 1. A method for treating cancer associated with over-expression of second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI (SMAC/Diablo) in a subject in need thereof, comprising administering to the subject an effective amount of at least one agent that inhibits the expression and/or activity of the SMAC/Diablo, wherein the agent is an inhibitory peptide targeted to a cell nucleus and/or mitochondrion or a pharmaceutical composition comprising same, the peptide is derived from hSMAC/Diablo-interacting protein and having an amino acid sequence at least 80% homologous to an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, analogs, derivatives and/or fragments thereof, and wherein the inhibitory peptide consists of 10-50 amino acids.
 2. The method of claim 1, wherein the inhibiting peptide is a conjugate comprising a peptide derived from hSMAC/Diablo-interacting protein having an amino acid sequence selected from the group consisting of SEQ ID NOs:46-67, and a mitochondrion and/or nucleus targeting moiety.
 3. The method of claim 2, wherein at least one of the following exist: (a) the nucleus and/or mitochondrion targeting moiety each independently is linked to the N- or C-terminus of the peptide conjugate, directly or via a linker; (b) the nucleus and/or mitochondrion targeting peptide are linked to the N- or C-terminus of the peptide conjugate in tandem, directly or via a linker.
 4. The method of claim 2, wherein the peptide conjugate further comprises a cell penetration moiety enhancing the permeability of the conjugate through the cell plasma membrane.
 5. The method of claim 2, wherein the nucleus or mitochondrion targeting moiety is a peptide.
 6. The method of claim 5, wherein the nucleus targeting moiety comprises the amino acid sequence set forth in SEQ ID NO:68 and wherein the peptide conjugate comprises an amino acid sequence selected from the group consisting of SEQ ID NO:69, SEQ ID NO:70 and SEQ ID NO:71.
 7. The method of claim 5, wherein the mitochondrion targeting moiety comprises the amino acid sequence set forth in SEQ ID NO:72, and wherein the peptide conjugate comprises an amino acid sequence selected from the group consisting of SEQ ID NO:73 and SEQ ID NO:74.
 8. The method of claim 1, wherein the cancer is selected from the group consisting of lung cancer, breast cancer, colon cancer, lymphoma, sarcomas, stomach cancer, skin cancer, prostate cancer, testicular cancer, cervical cancer, pancreatic cancer, leukemia and renal cancer. 